diff --git a/xml/System.Data.SqlClient/SqlConnection.xml b/xml/System.Data.SqlClient/SqlConnection.xml index 2b93042bcbd..f31b83c181e 100644 --- a/xml/System.Data.SqlClient/SqlConnection.xml +++ b/xml/System.Data.SqlClient/SqlConnection.xml @@ -78,7 +78,7 @@ If the goes out of scope, it won't be closed. Therefore, you must explicitly close the connection by calling `Close` or `Dispose`. `Close` and `Dispose` are functionally equivalent. If the connection pooling value `Pooling` is set to `true` or `yes`, the underlying connection is returned back to the connection pool. On the other hand, if `Pooling` is set to `false` or `no`, the underlying connection to the server is actually closed. > [!NOTE] -> Login and logout events will not be raised on the server when a connection is fetched from or returned to the connection pool, because the connection is not actually closed when it is returned to the connection pool. For more information, see [SQL Server Connection Pooling (ADO.NET)](/dotnet/framework/data/adonet/sql-server-connection-pooling). +> Login and logout events will not be raised on the server when a connection is fetched from or returned to the connection pool, because the connection is not actually closed when it is returned to the connection pool. For more information, see [SQL Server Connection Pooling (ADO.NET)](/dotnet/framework/data/adonet/sql-server-connection-pooling). To ensure that connections are always closed, open the connection inside of a `using` block, as shown in the following code fragment. Doing so ensures that the connection is automatically closed when the code exits the block. @@ -99,7 +99,7 @@ using (SqlConnection connection = new SqlConnection(connectionString)) ``` > [!NOTE] -> To deploy high-performance applications, you must use connection pooling. When you use the .NET Framework Data Provider for SQL Server, you do not have to enable connection pooling because the provider manages this automatically, although you can modify some settings. For more information, see [SQL Server Connection Pooling (ADO.NET)](/dotnet/framework/data/adonet/sql-server-connection-pooling). +> To deploy high-performance applications, you must use connection pooling. When you use the .NET Framework Data Provider for SQL Server, you do not have to enable connection pooling because the provider manages this automatically, although you can modify some settings. For more information, see [SQL Server Connection Pooling (ADO.NET)](/dotnet/framework/data/adonet/sql-server-connection-pooling). If a is generated by the method executing a , the remains open when the severity level is 19 or less. When the severity level is 20 or greater, the server ordinarily closes the . However, the user can reopen the connection and continue. @@ -108,7 +108,7 @@ using (SqlConnection connection = new SqlConnection(connectionString)) For more information about handling warning and informational messages from the server, see [Connection Events](/dotnet/framework/data/adonet/connection-events). For more information about SQL Server engine errors and error messages, see [Database Engine Events and Errors](/sql/relational-databases/errors-events/database-engine-events-and-errors). > [!CAUTION] -> You can force TCP instead of shared memory. You can do that by prefixing tcp: to the server name in the connection string or you can use localhost. +> You can force TCP instead of shared memory. You can do that by prefixing tcp: to the server name in the connection string or you can use localhost. @@ -229,7 +229,7 @@ using (SqlConnection connection = new SqlConnection(connectionString)) |Properties|Initial value| |----------------|-------------------| -||`connectionString`| +|| `connectionString` | ||15| ||empty string ("")| ||empty string ("")| @@ -403,13 +403,13 @@ using (SqlConnection connection = new SqlConnection(connectionString)) You must explicitly commit or roll back the transaction using the or method. To make sure that the .NET Framework Data Provider for SQL Server transaction management model performs correctly, avoid using other transaction management models, such as the one provided by SQL Server. > [!NOTE] -> If you do not specify an isolation level, the default isolation level is used. To specify an isolation level with the method, use the overload that takes the `iso` parameter (). The isolation level set for a transaction persists after the transaction is completed and until the connection is closed or disposed. Setting the isolation level to **Snapshot** in a database where the snapshot isolation level is not enabled does not throw an exception. The transaction will complete using the default isolation level. +> If you do not specify an isolation level, the default isolation level is used. To specify an isolation level with the method, use the overload that takes the `iso` parameter (). The isolation level set for a transaction persists after the transaction is completed and until the connection is closed or disposed. Setting the isolation level to **Snapshot** in a database where the snapshot isolation level is not enabled does not throw an exception. The transaction will complete using the default isolation level. > [!CAUTION] -> If a transaction is started and a level 16 or higher error occurs on the server, the transaction will not be rolled back until the method is invoked. No exception is thrown on **ExecuteReader**. +> If a transaction is started and a level 16 or higher error occurs on the server, the transaction will not be rolled back until the method is invoked. No exception is thrown on **ExecuteReader**. > [!CAUTION] -> When your query returns a large amount of data and calls `BeginTransaction`, a is thrown because SQL Server does not allow parallel transactions when using MARS. To avoid this problem, always associate a transaction with the command, the connection, or both before any readers are open. +> When your query returns a large amount of data and calls `BeginTransaction`, a is thrown because SQL Server does not allow parallel transactions when using MARS. To avoid this problem, always associate a transaction with the command, the connection, or both before any readers are open. For more information on SQL Server transactions, see [Transactions (Transact-SQL)](/sql/t-sql/language-elements/transactions-transact-sql). @@ -480,9 +480,7 @@ using (SqlConnection connection = new SqlConnection(connectionString)) For more information on SQL Server transactions, see [Transactions (Transact-SQL)](/sql/t-sql/language-elements/transactions-transact-sql). > [!CAUTION] -> When your query returns a large amount of data and calls `BeginTransaction`, a is thrown because SQL Server does not allow parallel transactions when using MARS. To avoid this problem, always associate a transaction with the command, the connection, or both before any readers are open. - - +> When your query returns a large amount of data and calls `BeginTransaction`, a is thrown because SQL Server does not allow parallel transactions when using MARS. To avoid this problem, always associate a transaction with the command, the connection, or both before any readers are open. ## Examples The following example creates a and a . It also demonstrates how to use the , a , and methods. @@ -550,9 +548,7 @@ using (SqlConnection connection = new SqlConnection(connectionString)) For more information on SQL Server transactions, see [Transactions (Transact-SQL)](/sql/t-sql/language-elements/transactions-transact-sql). > [!CAUTION] -> When your query returns a large amount of data and calls `BeginTransaction`, a is thrown because SQL Server does not allow parallel transactions when using MARS. To avoid this problem, always associate a transaction with the command, the connection, or both before any readers are open. - - +> When your query returns a large amount of data and calls `BeginTransaction`, a is thrown because SQL Server does not allow parallel transactions when using MARS. To avoid this problem, always associate a transaction with the command, the connection, or both before any readers are open. ## Examples The following example creates a and a . It also demonstrates how to use the , a , and methods. @@ -618,14 +614,12 @@ using (SqlConnection connection = new SqlConnection(connectionString)) You must explicitly commit or roll back the transaction using the or method. To make sure that the SQL Server transaction management model performs correctly, avoid using other transaction management models, such as the one provided by SQL Server. > [!NOTE] -> After a transaction is committed or rolled back, the isolation level of the transaction persists for all subsequent commands that are in autocommit mode (the SQL Server default). This can produce unexpected results, such as an isolation level of REPEATABLE READ persisting and locking other users out of a row. To reset the isolation level to the default (READ COMMITTED), execute the Transact-SQL SET TRANSACTION ISOLATION LEVEL READ COMMITTED statement, or call followed immediately by . For more information on SQL Server isolation levels, see [Transaction Isolation Levels](/sql/t-sql/language-elements/transaction-isolation-levels). +> After a transaction is committed or rolled back, the isolation level of the transaction persists for all subsequent commands that are in autocommit mode (the SQL Server default). This can produce unexpected results, such as an isolation level of REPEATABLE READ persisting and locking other users out of a row. To reset the isolation level to the default (READ COMMITTED), execute the Transact-SQL SET TRANSACTION ISOLATION LEVEL READ COMMITTED statement, or call followed immediately by . For more information on SQL Server isolation levels, see [Transaction Isolation Levels](/sql/t-sql/language-elements/transaction-isolation-levels). For more information on SQL Server transactions, see [Transactions (Transact-SQL)](/sql/t-sql/language-elements/transactions-transact-sql). > [!CAUTION] -> When your query returns a large amount of data and calls `BeginTransaction`, a is thrown because SQL Server does not allow parallel transactions when using MARS. To avoid this problem, always associate a transaction with the command, the connection, or both before any readers are open. - - +> When your query returns a large amount of data and calls `BeginTransaction`, a is thrown because SQL Server does not allow parallel transactions when using MARS. To avoid this problem, always associate a transaction with the command, the connection, or both before any readers are open. ## Examples The following example creates a and a . It also demonstrates how to use the , a , and methods. @@ -690,8 +684,6 @@ using (SqlConnection connection = new SqlConnection(connectionString)) ## Remarks The value supplied in the `database` parameter must be a valid database name. The `database` parameter cannot contain a null value, an empty string, or a string with only blank characters. - - ## Examples The following example creates a and displays some of its read-only properties. @@ -1010,19 +1002,17 @@ The connection string contains . The method rolls back any pending transactions. It then releases the connection to the connection pool, or closes the connection if connection pooling is disabled. > [!NOTE] -> Pending transactions started using Transact-SQL or are automatically rolled back when the connection is reset if connection pooling is enabled. If connection pooling is off, the transaction is rolled back after `SqlConnection.Close` is called. Transactions started through are controlled through the `System.Transactions` infrastructure, and are not affected by `SqlConnection.Close`. +> Pending transactions started using Transact-SQL or are automatically rolled back when the connection is reset if connection pooling is enabled. If connection pooling is off, the transaction is rolled back after `SqlConnection.Close` is called. Transactions started through are controlled through the `System.Transactions` infrastructure, and are not affected by `SqlConnection.Close`. An application can call more than one time. No exception is generated. If the goes out of scope, it won't be closed. Therefore, you must explicitly close the connection by calling `Close` or `Dispose`. `Close` and `Dispose` are functionally equivalent. If the connection pooling value `Pooling` is set to `true` or `yes`, the underlying connection is returned back to the connection pool. On the other hand, if `Pooling` is set to `false` or `no`, the underlying connection to the server is closed. > [!NOTE] -> Login and logout events will not be raised on the server when a connection is fetched from or returned to the connection pool, because the connection is not actually closed when it is returned to the connection pool. For more information, see [SQL Server Connection Pooling (ADO.NET)](/dotnet/framework/data/adonet/sql-server-connection-pooling). +> Login and logout events will not be raised on the server when a connection is fetched from or returned to the connection pool, because the connection is not actually closed when it is returned to the connection pool. For more information, see [SQL Server Connection Pooling (ADO.NET)](/dotnet/framework/data/adonet/sql-server-connection-pooling). > [!CAUTION] -> Do not call `Close` or `Dispose` on a Connection, a DataReader, or any other managed object in the `Finalize` method of your class. In a finalizer, you should only release unmanaged resources that your class owns directly. If your class does not own any unmanaged resources, do not include a `Finalize` method in your class definition. For more information, see [Garbage Collection](/dotnet/standard/garbage-collection/). - - +> Do not call `Close` or `Dispose` on a Connection, a DataReader, or any other managed object in the `Finalize` method of your class. In a finalizer, you should only release unmanaged resources that your class owns directly. If your class does not own any unmanaged resources, do not include a `Finalize` method in your class definition. For more information, see [Garbage Collection](/dotnet/standard/garbage-collection/). ## Examples The following example creates a , opens it, displays some of its properties. The connection is automatically closed at the end of the `using` block. @@ -1217,7 +1207,7 @@ The is similar to You can use the property to connect to a database. The following example illustrates a typical connection string. -``` +```txt "Persist Security Info=False;Integrated Security=true;Initial Catalog=Northwind;server=(local)" ``` @@ -1239,72 +1229,66 @@ The is similar to The following table lists the valid names for keyword values within the . -|Keyword|Default|Description| -|-------------|-------------|-----------------| -|Addr|N/A|Synonym of **Data Source**.| -|Address|N/A|Synonym of **Data Source**.| -|App|N/A|Synonym of **Application Name**.| -|Application Name|N/A|The name of the application, or '.NET SQLClient Data Provider' if no application name is provided.

An application name can be 128 characters or less.| -|`ApplicationIntent`|`ReadWrite`|Declares the application workload type when connecting to a server. Possible values are `ReadOnly` and `ReadWrite`. For example:

`ApplicationIntent=ReadOnly`

For more information about SqlClient support for Always On Availability Groups, see [SqlClient Support for High Availability, Disaster Recovery](/dotnet/framework/data/adonet/sql/sqlclient-support-for-high-availability-disaster-recovery).| -|Asynchronous Processing

-or-

Async|'false'|When `true`, enables asynchronous operation support. Recognized values are `true`, `false`, `yes`, and `no`.

This property is ignored beginning in .NET Framework 4.5. For more information about SqlClient support for asynchronous programming, see [Asynchronous Programming](/dotnet/framework/data/adonet/asynchronous-programming).| -|AttachDBFilename

-or-

Extended Properties

-or-

Initial File Name|N/A|The name of the primary database file, including the full path name of an attachable database. AttachDBFilename is only supported for primary data files with an .mdf extension.

If the value of the AttachDBFileName key is specified in the connection string, the database is attached and becomes the default database for the connection.

If this key is not specified and if the database was previously attached, the database will not be reattached. The previously attached database will be used as the default database for the connection.

If this key is specified together with the AttachDBFileName key, the value of this key will be used as the alias. However, if the name is already used in another attached database, the connection will fail.

The path may be absolute or relative by using the DataDirectory substitution string. If DataDirectory is used, the database file must exist within a subdirectory of the directory pointed to by the substitution string. **Note:** Remote server, HTTP, and UNC path names are not supported.

The database name must be specified with the keyword 'database' (or one of its aliases) as in the following:

`"AttachDbFileName=|DataDirectory|\data\YourDB.mdf;integrated security=true;database=YourDatabase"`

An error will be generated if a log file exists in the same directory as the data file and the 'database' keyword is used when attaching the primary data file. In this case, remove the log file. Once the database is attached, a new log file will be automatically generated based on the physical path.| -|Authentication|N/A|The authentication method used for [Connecting to SQL Database By Using Azure Active Directory Authentication](/azure/azure-sql/database/authentication-aad-overview#connect-by-using-azure-ad-identities).

Valid values are:

Active Directory Integrated, Active Directory Password, Sql Password.| -|Column Encryption Setting|N/A|Enables or disables [Always Encrypted](/sql/relational-databases/security/encryption/always-encrypted-database-engine?view=sql-server-2017) functionality for the connection.| -|Connect Timeout

-or-

Connection Timeout

-or-

Timeout|15|The length of time (in seconds) to wait for a connection to the server before terminating the attempt and generating an error.

Valid values are greater than or equal to 0 and less than or equal to 2147483647.

When opening a connection to a Azure SQL Database, set the connection timeout to 30 seconds.| -|Connection Lifetime

-or-

Load Balance Timeout|0|When a connection is returned to the pool, its creation time is compared with the current time, and the connection is destroyed if that time span (in seconds) exceeds the value specified by `Connection Lifetime`. This is useful in clustered configurations to force load balancing between a running server and a server just brought online.

A value of zero (0) causes pooled connections to have the maximum connection timeout.| -|ConnectRetryCount|1|Controls the number of reconnection attempts after the client identifies an idle connection failure. Valid values are 0 to 255. The default is 1. 0 means do not attempt to reconnect (disable connection resiliency).

For additional information about connection resiliency, see [.NET SqlConnection parameters for connection retry](https://learn.microsoft.com/azure/azure-sql/database/troubleshoot-common-connectivity-issues?view=azuresql#net-sqlconnection-parameters-for-connection-retry) and [Technical Article - Idle Connection Resiliency](https://download.microsoft.com/download/D/2/0/D20E1C5F-72EA-4505-9F26-FEF9550EFD44/Idle%20Connection%20Resiliency.docx).| -|ConnectRetryInterval|10|Specifies the time between each connection retry attempt (ConnectRetryCount). Valid values are 1 to 60 seconds (default=10), applied after the first reconnection attempt. When a broken connection is detected, the client immediately attempts to reconnect; this is the first reconnection attempt and only occurs if ConnectRetryCount is greater than 0. If the first reconnection attempt fails and ConnectRetryCount is greater than 1, the client waits ConnectRetryInterval to try the second and subsequent reconnection attempts.

For additional information about connection resiliency, see [.NET SqlConnection parameters for connection retry](https://learn.microsoft.com/azure/azure-sql/database/troubleshoot-common-connectivity-issues?view=azuresql#net-sqlconnection-parameters-for-connection-retry) and [Technical Article - Idle Connection Resiliency](https://download.microsoft.com/download/D/2/0/D20E1C5F-72EA-4505-9F26-FEF9550EFD44/Idle%20Connection%20Resiliency.docx).| -|Context Connection|'false'|`true` if an in-process connection to SQL Server should be made.| -|Current Language

-or-

Language|N/A|Sets the language used for database server warning or error messages.

The language name can be 128 characters or less.| -|Data Source

-or-

Server

-or-

Address

-or-

Addr

-or-

Network Address|N/A|The name or network address of the instance of SQL Server to which to connect. The port number can be specified after the server name:

`server=tcp:servername, portnumber`

When specifying a local instance, always use (local). To force a protocol, add one of the following prefixes:

`np:(local), tcp:(local), lpc:(local)`

Beginning in .NET Framework 4.5, you can also connect to a LocalDB database as follows:

`server=(localdb)\\myInstance`

For more information about LocalDB, see [SqlClient Support for LocalDB](/dotnet/framework/data/adonet/sql/sqlclient-support-for-localdb).

**Data Source** must use the TCP format or the Named Pipes format.

TCP format is as follows:

- tcp:\\\
- tcp:\,\

The TCP format must start with the prefix "tcp:" and is followed by the database instance, as specified by a host name and an instance name. This format is not applicable when connecting to Azure SQL Database. TCP is automatically selected for connections to Azure SQL Database when no protocol is specified.

The host name MUST be specified in one of the following ways:

- NetBIOSName
- IPv4Address
- IPv6Address

The instance name is used to resolve to a particular TCP/IP port number on which a database instance is hosted. Alternatively, specifying a TCP/IP port number directly is also allowed. If both instance name and port number are not present, the default database instance is used.

The Named Pipes format is as follows:

- np:\\\\\pipe\\

The Named Pipes format MUST start with the prefix "np:" and is followed by a named pipe name.

The host name MUST be specified in one of the following ways:

- NetBIOSName
- IPv4Address
- IPv6Address

The pipe name is used to identify the database instance to which the .NET Framework application will be connected.

If the value of the **Network** key is specified, the prefixes "tcp:" and "np:" should not be specified. **Note:** You can force the use of TCP instead of shared memory, either by prefixing **tcp:** to the server name in the connection string, or by using **localhost**.| -|Encrypt|'false'|When `true`, SQL Server uses SSL encryption for all data sent between the client and server if the server has a certificate installed. Recognized values are `true`, `false`, `yes`, and `no`. For more information, see [Connection String Syntax](/dotnet/framework/data/adonet/connection-string-syntax).

Beginning in .NET Framework 4.5, when `TrustServerCertificate` is false and `Encrypt` is true, the server name (or IP address) in a SQL Server SSL certificate must exactly match the server name (or IP address) specified in the connection string. Otherwise, the connection attempt will fail.| -|Enlist|'true'|`true` indicates that the SQL Server connection pooler automatically enlists the connection in the creation thread's current transaction context.| -|Failover Partner|N/A|The name of the failover partner server where database mirroring is configured.

If the value of this key is "", then **Initial Catalog** must be present, and its value must not be "".

The server name can be 128 characters or less.

If you specify a failover partner but the failover partner server is not configured for database mirroring and the primary server (specified with the Server keyword) is not available, then the connection will fail.

If you specify a failover partner and the primary server is not configured for database mirroring, the connection to the primary server (specified with the Server keyword) will succeed if the primary server is available.| -|Initial Catalog

-or-

Database|N/A|The name of the database.

The database name can be 128 characters or less.| -|Integrated Security

-or-

Trusted_Connection|'false'|When `false`, User ID and Password are specified in the connection. When `true`, the current Windows account credentials are used for authentication.

Recognized values are `true`, `false`, `yes`, `no`, and `sspi` (strongly recommended), which is equivalent to `true`.

If User ID and Password are specified and Integrated Security is set to true, the User ID and Password will be ignored and Integrated Security will be used.

is a more secure way to specify credentials for a connection that uses SQL Server Authentication (`Integrated Security=false`).| -|Max Pool Size|100|The maximum number of connections that are allowed in the pool.

Valid values are greater than or equal to 1. Values that are less than **Min Pool Size** generate an error.| -|Min Pool Size|0|The minimum number of connections that are allowed in the pool.

Valid values are greater than or equal to 0. Zero (0) in this field means no minimum connections are initially opened.

Values that are greater than **Max Pool Size** generate an error.| -|MultipleActiveResultSets|'false'|When `true`, an application can maintain multiple active result sets (MARS). When `false`, an application must process or cancel all result sets from one batch before it can execute any other batch on that connection.

Recognized values are `true` and `false`.

For more information, see [Multiple Active Result Sets (MARS)](/dotnet/framework/data/adonet/sql/multiple-active-result-sets-mars).| -|`MultiSubnetFailover`|FALSE|Always specify `multiSubnetFailover=True` when connecting to the availability group listener of a SQL Server 2012 (or later) availability group or a SQL Server 2012 (or later) Failover Cluster Instance. `multiSubnetFailover=True` configures SqlClient to provide faster detection of and connection to the (currently) active server. Possible values are `Yes` and `No`, `True` and `False` or `1` and `0`. For example:

`MultiSubnetFailover=True`

The default is `False`. For more information about SqlClient's support for Always On AGs, see [SqlClient Support for High Availability, Disaster Recovery](/dotnet/framework/data/adonet/sql/sqlclient-support-for-high-availability-disaster-recovery).| -|Network Library

-or-

Network

-or-

Net|N/A|The network library used to establish a connection to an instance of SQL Server. Supported values include:

dbnmpntw (Named Pipes)

dbmsrpcn (Multiprotocol, Windows RPC)

dbmsadsn (Apple Talk)

dbmsgnet (VIA)

dbmslpcn (Shared Memory)

dbmsspxn (IPX/SPX)

dbmssocn (TCP/IP)

Dbmsvinn (Banyan Vines)

The corresponding network DLL must be installed on the system to which you connect. If you do not specify a network and you use a local server (for example, "." or "(local)"), shared memory is used. In this example, the network library is Win32 Winsock TCP/IP (dbmssocn), and 1433 is the port being used.

`Network Library=dbmssocn;Data Source=000.000.000.000,1433;`| -|Packet Size|8000|Size in bytes of the network packets used to communicate with an instance of SQL Server.

The packet size can be greater than or equal to 512 and less than or equal to 32768.| -|Password

-or-

PWD|N/A|The password for the SQL Server account logging on. Not recommended. To maintain a high level of security, we strongly recommend that you use the `Integrated Security` or `Trusted_Connection` keyword instead. is a more secure way to specify credentials for a connection that uses SQL Server Authentication.

The password must be 128 characters or less.| -|Persist Security Info

-or-

PersistSecurityInfo|'false'|When set to `false` or `no` (strongly recommended), security-sensitive information, such as the password, is not returned as part of the connection if the connection is open or has ever been in an open state. Resetting the connection string resets all connection string values including the password. Recognized values are `true`, `false`, `yes`, and `no`.| -|PoolBlockingPeriod|Auto|Sets the blocking period behavior for a connection pool. See property for details.| -|Pooling|'true'|When the value of this key is set to true, any newly created connection will be added to the pool when closed by the application. In a next attempt to open the same connection, that connection will be drawn from the pool.

Connections are considered the same if they have the same connection string. Different connections have different connection strings.

The value of this key can be "true", "false", "yes", or "no".| -|Replication|'false'|`true` if replication is supported using the connection.| -|Transaction Binding|Implicit Unbind|Controls connection association with an enlisted `System.Transactions` transaction.

Possible values are:

`Transaction Binding=Implicit Unbind;`

`Transaction Binding=Explicit Unbind;`

Implicit Unbind causes the connection to detach from the transaction when it ends. After detaching, additional requests on the connection are performed in autocommit mode. The `System.Transactions.Transaction.Current` property is not checked when executing requests while the transaction is active. After the transaction has ended, additional requests are performed in autocommit mode.

If the system ends the transaction (in the scope of a using block) before the last command completes, it will throw .

Explicit Unbind causes the connection to remain attached to the transaction until the connection is closed or an explicit `SqlConnection.TransactionEnlist(null)` is called. Beginning in .NET Framework 4, changes to Implicit Unbind make Explicit Unbind obsolete. An `InvalidOperationException` is thrown if `Transaction.Current` is not the enlisted transaction or if the enlisted transaction is not active.| -|TransparentNetworkIPResolution|See description.|When the value of this key is set to `true`, the application is required to retrieve all IP addresses for a particular DNS entry and attempt to connect with the first one in the list. If the connection is not established within 0.5 seconds, the application will try to connect to all others in parallel. When the first answers, the application will establish the connection with the respondent IP address.

If the `MultiSubnetFailover` key is set to `true`, `TransparentNetworkIPResolution` is ignored.

If the `Failover Partner` key is set, `TransparentNetworkIPResolution` is ignored.

The value of this key must be `true`, `false`, `yes`, or `no`.

A value of `yes` is treated the same as a value of `true`.

A value of `no` is treated the same as a value of `false`.

The default values are as follows:

  • `false` when:

    • Connecting to Azure SQL Database where the data source ends with:

      • .database.chinacloudapi.cn
      • .database.usgovcloudapi.net
      • .database.cloudapi.de
      • .database.windows.net
    • `Authentication` is 'Active Directory Password' or 'Active Directory Integrated'
  • `true` in all other cases.
| -|TrustServerCertificate|'false'|When set to `true`, SSL is used to encrypt the channel when bypassing walking the certificate chain to validate trust. If TrustServerCertificate is set to `true` and Encrypt is set to `false`, the channel is not encrypted. Recognized values are `true`, `false`, `yes`, and `no`. For more information, see [Connection String Syntax](/dotnet/framework/data/adonet/connection-string-syntax).| -|Type System Version|N/A|A string value that indicates the type system the application expects. The functionality available to a client application is dependent on the version of SQL Server and the compatibility level of the database. Explicitly setting the type system version that the client application was written for avoids potential problems that could cause an application to break if a different version of SQL Server is used. **Note:** The type system version cannot be set for common language runtime (CLR) code executing in-process in SQL Server. For more information, see [SQL Server Common Language Runtime Integration](/dotnet/framework/data/adonet/sql/sql-server-common-language-runtime-integration).

Possible values are:

`Type System Version=SQL Server 2012;`

`Type System Version=SQL Server 2008;`

`Type System Version=SQL Server 2005;`

`Type System Version=Latest;`

`Type System Version=SQL Server 2012;` specifies that the application will require version 11.0.0.0 of Microsoft.SqlServer.Types.dll. The other `Type System Version` settings will require version 10.0.0.0 of Microsoft.SqlServer.Types.dll.

`Latest` is obsolete and should not be used. `Latest` is equivalent to `Type System Version=SQL Server 2008;`.| -|User ID

-or-

UID

-or-

User|N/A|The SQL Server login account. Not recommended. To maintain a high level of security, we strongly recommend that you use the `Integrated Security` or `Trusted_Connection` keywords instead. is a more secure way to specify credentials for a connection that uses SQL Server Authentication.

The user ID must be 128 characters or less.| -|User Instance|'false'|A value that indicates whether to redirect the connection from the default SQL Server Express instance to a runtime-initiated instance running under the account of the caller.| -|Workstation ID

-or-

WSID|The local computer name|The name of the workstation connecting to SQL Server.

The ID must be 128 characters or less.| - - The following list contains the valid names for connection pooling values within the . For more information, see [SQL Server Connection Pooling (ADO.NET)](/dotnet/framework/data/adonet/sql-server-connection-pooling). - -- Connection Lifetime (or Load Balance Timeout) - -- Enlist - -- Max Pool Size - -- Min Pool Size - -- Pooling - - When you are setting keyword or connection pooling values that require a Boolean value, you can use 'yes' instead of 'true', and 'no' instead of 'false'. Integer values are represented as strings. +| Keyword | Default | Description | +|--------------------|---------|----------------------------------| +| `Addr` | N/A | Synonym of **Data Source**. | +| `Address` | N/A | Synonym of **Data Source**. | +| `App` | N/A | Synonym of **Application Name**. | +| `Application Name` | N/A | The name of the application, or '.NET SQLClient Data Provider' if no application name is provided.

An application name can be 128 characters or less. | +| `ApplicationIntent` | `ReadWrite` |Declares the application workload type when connecting to a server. Possible values are `ReadOnly` and `ReadWrite`. For example:

`ApplicationIntent=ReadOnly`

For more information about SqlClient support for Always On Availability Groups, see [SqlClient Support for High Availability, Disaster Recovery](/dotnet/framework/data/adonet/sql/sqlclient-support-for-high-availability-disaster-recovery).| +| `Asynchronous Processing`
-or-
`Async` |'false'|When `true`, enables asynchronous operation support. Recognized values are `true`, `false`, `yes`, and `no`.

This property is ignored beginning in .NET Framework 4.5. For more information about SqlClient support for asynchronous programming, see [Asynchronous Programming](/dotnet/framework/data/adonet/asynchronous-programming).| +| `AttachDBFilename`
-or-
`Extended Properties`
-or-
`Initial File Name` |N/A|The name of the primary database file, including the full path name of an attachable database. AttachDBFilename is only supported for primary data files with an .mdf extension.

If the value of the AttachDBFileName key is specified in the connection string, the database is attached and becomes the default database for the connection.

If this key is not specified and if the database was previously attached, the database will not be reattached. The previously attached database will be used as the default database for the connection.

If this key is specified together with the AttachDBFileName key, the value of this key will be used as the alias. However, if the name is already used in another attached database, the connection will fail.

The path may be absolute or relative by using the DataDirectory substitution string. If DataDirectory is used, the database file must exist within a subdirectory of the directory pointed to by the substitution string. **Note:** Remote server, HTTP, and UNC path names are not supported.

The database name must be specified with the keyword 'database' (or one of its aliases) as in the following:

`"AttachDbFileName=|DataDirectory|\data\YourDB.mdf;integrated security=true;database=YourDatabase"`

An error will be generated if a log file exists in the same directory as the data file and the 'database' keyword is used when attaching the primary data file. In this case, remove the log file. Once the database is attached, a new log file will be automatically generated based on the physical path.| +| `Authentication` |N/A|The authentication method used for [Connecting to SQL Database By Using Azure Active Directory Authentication](/azure/azure-sql/database/authentication-aad-overview#connect-by-using-azure-ad-identities).

Valid values are:

Active Directory Integrated, Active Directory Password, Sql Password.| +| `Column Encryption Setting` |N/A|Enables or disables [Always Encrypted](/sql/relational-databases/security/encryption/always-encrypted-database-engine?view=sql-server-2017) functionality for the connection.| +| `Connect Timeout`
-or-
`Connection Timeout`
-or-
`Timeout` |15|The length of time (in seconds) to wait for a connection to the server before terminating the attempt and generating an error.

Valid values are greater than or equal to 0 and less than or equal to 2147483647.

When opening a connection to a Azure SQL Database, set the connection timeout to 30 seconds.| +| `Connection Lifetime`
-or-
`Load Balance Timeout` |0|When a connection is returned to the pool, its creation time is compared with the current time, and the connection is destroyed if that time span (in seconds) exceeds the value specified by `Connection Lifetime`. This is useful in clustered configurations to force load balancing between a running server and a server just brought online.

A value of zero (0) causes pooled connections to have the maximum connection timeout.| +| `ConnectRetryCount` |1|Controls the number of reconnection attempts after the client identifies an idle connection failure. Valid values are 0 to 255. The default is 1. 0 means do not attempt to reconnect (disable connection resiliency).

For additional information about connection resiliency, see [.NET SqlConnection parameters for connection retry](/azure/azure-sql/database/troubleshoot-common-connectivity-issues?view=azuresql#net-sqlconnection-parameters-for-connection-retry) and [Technical Article - Idle Connection Resiliency](https://download.microsoft.com/download/D/2/0/D20E1C5F-72EA-4505-9F26-FEF9550EFD44/Idle%20Connection%20Resiliency.docx).| +| `ConnectRetryInterval` |10|Specifies the time between each connection retry attempt (ConnectRetryCount). Valid values are 1 to 60 seconds (default=10), applied after the first reconnection attempt. When a broken connection is detected, the client immediately attempts to reconnect; this is the first reconnection attempt and only occurs if ConnectRetryCount is greater than 0. If the first reconnection attempt fails and ConnectRetryCount is greater than 1, the client waits ConnectRetryInterval to try the second and subsequent reconnection attempts.

For additional information about connection resiliency, see [.NET SqlConnection parameters for connection retry](/azure/azure-sql/database/troubleshoot-common-connectivity-issues?view=azuresql#net-sqlconnection-parameters-for-connection-retry) and [Technical Article - Idle Connection Resiliency](https://download.microsoft.com/download/D/2/0/D20E1C5F-72EA-4505-9F26-FEF9550EFD44/Idle%20Connection%20Resiliency.docx).| +| `Context Connection` |'false'| `true` if an in-process connection to SQL Server should be made.| +| `Current Language`
-or-
`Language` |N/A|Sets the language used for database server warning or error messages.

The language name can be 128 characters or less.| +| `Data Source`
-or-
`Server`
-or-
`Address`
-or-
`Addr`
-or-
`Network Address` |N/A|The name or network address of the instance of SQL Server to which to connect. The port number can be specified after the server name:

`server=tcp:servername, portnumber`

When specifying a local instance, always use (local). To force a protocol, add one of the following prefixes:

`np:(local), tcp:(local), lpc:(local)`

Beginning in .NET Framework 4.5, you can also connect to a LocalDB database as follows:

`server=(localdb)\\myInstance`

For more information about LocalDB, see [SqlClient Support for LocalDB](/dotnet/framework/data/adonet/sql/sqlclient-support-for-localdb).

**Data Source** must use the TCP format or the Named Pipes format.

TCP format is as follows:

- tcp:\\\
- tcp:\,\

The TCP format must start with the prefix "tcp:" and is followed by the database instance, as specified by a host name and an instance name. This format is not applicable when connecting to Azure SQL Database. TCP is automatically selected for connections to Azure SQL Database when no protocol is specified.

The host name MUST be specified in one of the following ways:

- NetBIOSName
- IPv4Address
- IPv6Address

The instance name is used to resolve to a particular TCP/IP port number on which a database instance is hosted. Alternatively, specifying a TCP/IP port number directly is also allowed. If both instance name and port number are not present, the default database instance is used.

The Named Pipes format is as follows:

- np:\\\\\pipe\\

The Named Pipes format MUST start with the prefix "np:" and is followed by a named pipe name.

The host name MUST be specified in one of the following ways:

- NetBIOSName
- IPv4Address
- IPv6Address

The pipe name is used to identify the database instance to which the .NET Framework application will be connected.

If the value of the **Network** key is specified, the prefixes "tcp:" and "np:" should not be specified. **Note:** You can force the use of TCP instead of shared memory, either by prefixing **tcp:** to the server name in the connection string, or by using **localhost**.| +| `Encrypt` |'false'|When `true`, SQL Server uses SSL encryption for all data sent between the client and server if the server has a certificate installed. Recognized values are `true`, `false`, `yes`, and `no`. For more information, see [Connection String Syntax](/dotnet/framework/data/adonet/connection-string-syntax).

Beginning in .NET Framework 4.5, when `TrustServerCertificate` is false and `Encrypt` is true, the server name (or IP address) in a SQL Server SSL certificate must exactly match the server name (or IP address) specified in the connection string. Otherwise, the connection attempt will fail.| +| `Enlist` |'true'| `true` indicates that the SQL Server connection pooler automatically enlists the connection in the creation thread's current transaction context.| +| `Failover Partner` |N/A|The name of the failover partner server where database mirroring is configured.

If the value of this key is "", then **Initial Catalog** must be present, and its value must not be "".

The server name can be 128 characters or less.

If you specify a failover partner but the failover partner server is not configured for database mirroring and the primary server (specified with the Server keyword) is not available, then the connection will fail.

If you specify a failover partner and the primary server is not configured for database mirroring, the connection to the primary server (specified with the Server keyword) will succeed if the primary server is available.| +| `Initial Catalog`
-or-
`Database` |N/A|The name of the database.

The database name can be 128 characters or less.| +| `Integrated Security`
-or-
`Trusted_Connection` |'false'|When `false`, User ID and Password are specified in the connection. When `true`, the current Windows account credentials are used for authentication.

Recognized values are `true`, `false`, `yes`, `no`, and `sspi` (strongly recommended), which is equivalent to `true`.

If User ID and Password are specified and Integrated Security is set to true, the User ID and Password will be ignored and Integrated Security will be used.

is a more secure way to specify credentials for a connection that uses SQL Server Authentication (`Integrated Security=false`).| +| `Max Pool Size` |100|The maximum number of connections that are allowed in the pool.

Valid values are greater than or equal to 1. Values that are less than **Min Pool Size** generate an error.| +| `Min Pool Size` |0|The minimum number of connections that are allowed in the pool.

Valid values are greater than or equal to 0. Zero (0) in this field means no minimum connections are initially opened.

Values that are greater than **Max Pool Size** generate an error.| +| `MultipleActiveResultSets` |'false'|When `true`, an application can maintain multiple active result sets (MARS). When `false`, an application must process or cancel all result sets from one batch before it can execute any other batch on that connection.

Recognized values are `true` and `false`.

For more information, see [Multiple Active Result Sets (MARS)](/dotnet/framework/data/adonet/sql/multiple-active-result-sets-mars).| +| `MultiSubnetFailover` |FALSE|Always specify `multiSubnetFailover=True` when connecting to the availability group listener of a SQL Server 2012 (or later) availability group or a SQL Server 2012 (or later) Failover Cluster Instance. `multiSubnetFailover=True` configures SqlClient to provide faster detection of and connection to the (currently) active server. Possible values are `Yes` and `No`, `True` and `False` or `1` and `0`. For example:

`MultiSubnetFailover=True`

The default is `False`. For more information about SqlClient's support for Always On AGs, see [SqlClient Support for High Availability, Disaster Recovery](/dotnet/framework/data/adonet/sql/sqlclient-support-for-high-availability-disaster-recovery).| +| `Network Library`
-or-
`Network`
-or-
`Net` |N/A|The network library used to establish a connection to an instance of SQL Server. Supported values include:

dbnmpntw (Named Pipes)

dbmsrpcn (Multiprotocol, Windows RPC)

dbmsadsn (Apple Talk)

dbmsgnet (VIA)

dbmslpcn (Shared Memory)

dbmsspxn (IPX/SPX)

dbmssocn (TCP/IP)

Dbmsvinn (Banyan Vines)

The corresponding network DLL must be installed on the system to which you connect. If you do not specify a network and you use a local server (for example, "." or "(local)"), shared memory is used. In this example, the network library is Win32 Winsock TCP/IP (dbmssocn), and 1433 is the port being used.

`Network Library=dbmssocn;Data Source=000.000.000.000,1433;` | +| `Packet Size` |8000|Size in bytes of the network packets used to communicate with an instance of SQL Server.

The packet size can be greater than or equal to 512 and less than or equal to 32768.| +| `Password`
-or-
`PWD` |N/A|The password for the SQL Server account logging on. Not recommended. To maintain a high level of security, we strongly recommend that you use the `Integrated Security` or `Trusted_Connection` keyword instead. is a more secure way to specify credentials for a connection that uses SQL Server Authentication.

The password must be 128 characters or less.| +| `Persist Security Info`
-or-
`PersistSecurityInfo` |'false'|When set to `false` or `no` (strongly recommended), security-sensitive information, such as the password, is not returned as part of the connection if the connection is open or has ever been in an open state. Resetting the connection string resets all connection string values including the password. Recognized values are `true`, `false`, `yes`, and `no`.| +| `PoolBlockingPeriod` |Auto|Sets the blocking period behavior for a connection pool. See property for details.| +| `Pooling` |'true'|When the value of this key is set to true, any newly created connection will be added to the pool when closed by the application. In a next attempt to open the same connection, that connection will be drawn from the pool.

Connections are considered the same if they have the same connection string. Different connections have different connection strings.

The value of this key can be "true", "false", "yes", or "no".| +| `Replication` |'false'| `true` if replication is supported using the connection.| +| `Transaction Binding` |Implicit Unbind|Controls connection association with an enlisted `System.Transactions` transaction.

Possible values are:

`Transaction Binding=Implicit Unbind;`

`Transaction Binding=Explicit Unbind;`

Implicit Unbind causes the connection to detach from the transaction when it ends. After detaching, additional requests on the connection are performed in autocommit mode. The `System.Transactions.Transaction.Current` property is not checked when executing requests while the transaction is active. After the transaction has ended, additional requests are performed in autocommit mode.

If the system ends the transaction (in the scope of a using block) before the last command completes, it will throw .

Explicit Unbind causes the connection to remain attached to the transaction until the connection is closed or an explicit `SqlConnection.TransactionEnlist(null)` is called. Beginning in .NET Framework 4, changes to Implicit Unbind make Explicit Unbind obsolete. An `InvalidOperationException` is thrown if `Transaction.Current` is not the enlisted transaction or if the enlisted transaction is not active.| +| `TransparentNetworkIPResolution` |See description.|When the value of this key is set to `true`, the application is required to retrieve all IP addresses for a particular DNS entry and attempt to connect with the first one in the list. If the connection is not established within 0.5 seconds, the application will try to connect to all others in parallel. When the first answers, the application will establish the connection with the respondent IP address.

If the `MultiSubnetFailover` key is set to `true`, `TransparentNetworkIPResolution` is ignored.

If the `Failover Partner` key is set, `TransparentNetworkIPResolution` is ignored.

The value of this key must be `true`, `false`, `yes`, or `no`.

A value of `yes` is treated the same as a value of `true`.

A value of `no` is treated the same as a value of `false`.

The default values are as follows:

  • `false` when:

    • Connecting to Azure SQL Database where the data source ends with:

      • .database.chinacloudapi.cn
      • .database.usgovcloudapi.net
      • .database.cloudapi.de
      • .database.windows.net
    • `Authentication` is 'Active Directory Password' or 'Active Directory Integrated'
  • `true` in all other cases.
| +| `TrustServerCertificate` |'false'|When set to `true`, SSL is used to encrypt the channel when bypassing walking the certificate chain to validate trust. If TrustServerCertificate is set to `true` and Encrypt is set to `false`, the channel is not encrypted. Recognized values are `true`, `false`, `yes`, and `no`. For more information, see [Connection String Syntax](/dotnet/framework/data/adonet/connection-string-syntax).| +| `Type System Version` |N/A|A string value that indicates the type system the application expects. The functionality available to a client application is dependent on the version of SQL Server and the compatibility level of the database. Explicitly setting the type system version that the client application was written for avoids potential problems that could cause an application to break if a different version of SQL Server is used. **Note:** The type system version cannot be set for common language runtime (CLR) code executing in-process in SQL Server. For more information, see [SQL Server Common Language Runtime Integration](/dotnet/framework/data/adonet/sql/sql-server-common-language-runtime-integration).

Possible values are:

`Type System Version=SQL Server 2012;`

`Type System Version=SQL Server 2008;`

`Type System Version=SQL Server 2005;`

`Type System Version=Latest;`

`Type System Version=SQL Server 2012;` specifies that the application will require version 11.0.0.0 of Microsoft.SqlServer.Types.dll. The other `Type System Version` settings will require version 10.0.0.0 of Microsoft.SqlServer.Types.dll.

`Latest` is obsolete and should not be used. `Latest` is equivalent to `Type System Version=SQL Server 2008;`.| +| `User ID`
-or-
`UID`
-or-
`User` |N/A|The SQL Server login account. Not recommended. To maintain a high level of security, we strongly recommend that you use the `Integrated Security` or `Trusted_Connection` keywords instead. is a more secure way to specify credentials for a connection that uses SQL Server Authentication.

The user ID must be 128 characters or less.| +| `User Instance` |'false'|A value that indicates whether to redirect the connection from the default SQL Server Express instance to a runtime-initiated instance running under the account of the caller.| +| `Workstation ID`
-or-
`WSID` |The local computer name|The name of the workstation connecting to SQL Server.

The ID must be 128 characters or less.| + + The following list contains the valid names for connection pooling values within the . For more information, see [SQL Server Connection Pooling (ADO.NET)](/dotnet/framework/data/adonet/sql-server-connection-pooling). + +- `Connection Lifetime` (or `Load Balance Timeout`) +- `Enlist` +- `Max Pool Size` +- `Min Pool Size` +- `Pooling` + + When you set keyword or connection pooling values that require a Boolean value, you can use `yes` instead of `true`, and `no` instead of `false`. Integer values are represented as strings. > [!NOTE] -> The .NET Framework Data Provider for SQL Server uses its own protocol to communicate with SQL Server. Therefore, it does not support the use of an ODBC data source name (DSN) when connecting to SQL Server because it does not add an ODBC layer. +> The .NET Framework Data Provider for SQL Server uses its own protocol to communicate with SQL Server. Therefore, it does not support the use of an ODBC data source name (DSN) when connecting to SQL Server because it does not add an ODBC layer. > [!NOTE] -> Universal data link (UDL) files are not supported for the .NET Framework Data Provider for SQL Server. +> Universal data link (UDL) files are not supported for the .NET Framework Data Provider for SQL Server. > [!CAUTION] -> In this release, the application should use caution when constructing a connection string based on user input (for example when retrieving user ID and password information from a dialog box, and appending it to the connection string). The application should make sure that a user cannot embed additional connection string parameters in these values (for example, entering a password as "validpassword;database=somedb" in an attempt to attach to a different database). If you need to construct connection strings based on user input, use the new , which validates the connection string and helps to eliminate this problem. See [Connection String Builders](/dotnet/framework/data/adonet/connection-string-builders) for more information. - - +> Use caution when constructing a connection string based on user input (for example when retrieving user ID and password information from a dialog box, and appending it to the connection string). Make sure that a user cannot embed additional connection string parameters in these values (for example, entering a password as "validpassword;database=somedb" in an attempt to attach to a different database). If you need to construct connection strings based on user input, use , which validates the connection string and helps to eliminate this problem. For more information, see [Connection String Builders](/dotnet/framework/data/adonet/connection-string-builders). ## Examples The following example creates a and sets the property before opening the connection. @@ -1510,15 +1494,15 @@ The is similar to An exception will be raised: -- If is set on an open connection. +- If is set on an open connection. -- If is set when `Context Connection=true`. +- If is set when `Context Connection=true`. -- If is set when `Integrated Security = true`. +- If is set when `Integrated Security = true`. -- If is set when the connection string uses `Password`. +- If is set when the connection string uses `Password`. -- If is set when the connection string uses `UserID`. +- If is set when the connection string uses `UserID`. ]]> @@ -1645,7 +1629,7 @@ The is similar to ## Remarks > [!NOTE] -> The property returns `null` if the connection string for the is "context connection=true". +> The property returns `null` if the connection string for the is "context connection=true". @@ -1840,7 +1824,7 @@ The is similar to When you set to `true`, errors that were previously treated as exceptions are now handled as events. All events fire immediately and are handled by the event handler. If is is set to `false`, then events are handled at the end of the procedure. > [!NOTE] -> An error with a severity level of 17 or above that causes the server to stop processing the command needs to be handled as an exception. In this case, an exception is thrown regardless of how the error is handled in the event. +> An error with a severity level of 17 or above that causes the server to stop processing the command needs to be handled as an exception. In this case, an exception is thrown regardless of how the error is handled in the event. For more information on working with events, see [Connection Events](/dotnet/framework/data/adonet/connection-events). For more information on errors generated by the SQL Server engine, see [Database Engine Errors](/sql/relational-databases/errors-events/database-engine-events-and-errors). @@ -1931,17 +1915,16 @@ The is similar to draws an open connection from the connection pool if one is available. Otherwise, it establishes a new connection to an instance of SQL Server. > [!NOTE] -> If the goes out of scope, it is not closed. Therefore, you must explicitly close the connection by calling . +> If the goes out of scope, it is not closed. Therefore, you must explicitly close the connection by calling . > [!NOTE] -> If you specify a port number other than 1433 when you are trying to connect to an instance of SQL Server and using a protocol other than TCP/IP, the method fails. To specify a port number other than 1433, include "server=machinename,port number" in the connection string, and use the TCP/IP protocol. +> If you specify a port number other than 1433 when you are trying to connect to an instance of SQL Server and using a protocol other than TCP/IP, the method fails. To specify a port number other than 1433, include "server=machinename,port number" in the connection string, and use the TCP/IP protocol. > [!NOTE] -> The .NET Framework Data Provider for SQL Server requires the Security permission with "Allows calls to unmanaged assemblies" enabled ( with set to `UnmanagedCode`) to open a with SQL Debugging enabled. +> The .NET Framework Data Provider for SQL Server requires the Security permission with "Allows calls to unmanaged assemblies" enabled ( with set to `UnmanagedCode`) to open a with SQL Debugging enabled.