Update README.md (#192)

Author: KirillKurdyukov

README.md

@@ -1,10 +1,15 @@
 [![Nuget](https://img.shields.io/nuget/v/Ydb.Sdk)](https://www.nuget.org/packages/Ydb.Sdk/)
 
 # YDB .NET SDK
-YDB client libraries for .NET.
+Provides an ADO.NET standard implementation for working with YDB, as well as native clients for lightweight interaction with YDB.
 
 ## Prerequisites
-.NET 6 or .NET 7
+.NET 6 or above
+
+## Features
+
+- **ADO.NET**: Full support for standard ADO.NET interfaces including DbConnection, DbCommand, DbDataReader, and more. This allows you to use familiar methods and patterns for database operations while leveraging the power and flexibility of YDB.
+- **QueryClient**: A lightweight, high-performance native client for direct interaction with YDB tables.
 
 ## Versioning
 
@@ -18,7 +23,48 @@ Major version zero (`0.y.z`) is considered prerelease and **do not guarantee any
 dotnet add package Ydb.Sdk
 ```
 
-## Usage
+## Usage ADO.NET
+
+Example of using ADO.NET to execute a SQL query against YDB:
+
+```c#
+var ydbConnectionBuilder = new YdbConnectionStringBuilder
+{
+    Host = "server",
+    Port = 2135,
+    Database = "/my-ydb",
+    UseTls = true,
+    CredentialsProvider = credentialsProvider // Credentials provider, see "Credentials" section
+};
+
+await using var connection = new YdbConnection(ydbConnectionBuilder);
+await connection.OpenAsync();
+
+var ydbCommand = connection.CreateCommand();
+ydbCommand.CommandText = """
+                         SELECT series_id, season_id, episode_id, air_date, title
+                         FROM episodes
+                         WHERE series_id = @series_id AND season_id > @season_id
+                         ORDER BY series_id, season_id, episode_id
+                         LIMIT @limit_size;
+                         """;
+ydbCommand.Parameters.Add(new YdbParameter("$series_id", DbType.UInt64, 1U));
+ydbCommand.Parameters.Add(new YdbParameter("$season_id", DbType.UInt64, 1U));
+ydbCommand.Parameters.Add(new YdbParameter("$limit_size", DbType.UInt64, 3U));
+
+var ydbDataReader = await ydbCommand.ExecuteReaderAsync();
+
+_logger.LogInformation("Selected rows:");
+while (await ydbDataReader.ReadAsync())
+{
+    _logger.LogInformation(
+        "series_id: {series_id}, season_id: {season_id}, episode_id: {episode_id}, air_date: {air_date}, title: {title}",
+        ydbDataReader.GetUint64(0), ydbDataReader.GetUint64(1), ydbDataReader.GetUint64(2),
+        ydbDataReader.GetDateTime(3), ydbDataReader.GetString(4));
+}
+```
+
+## Usage Native clients
 
 To begin your work with YDB, create an instance of `Ydb.Sdk.Driver` class:
 ```c#
@@ -36,6 +82,8 @@ using var driver = new Driver(
 await driver.Initialize(); // Make sure to await driver initialization
 ```
 
+After you have driver instance, you can use it to create clients for different YDB services.
+
 ### Credentials
 YDB SDK provides several standard ways for authentication:
 1) `Ydb.Sdk.Auth.AnonymousProvider`. Anonymous YDB access, mainly for tests purposes.
@@ -44,17 +92,15 @@ YDB SDK provides several standard ways for authentication:
 
 For Yandex.Cloud specific authentication methods, consider using **[ydb-dotnet-yc](https://github.com/ydb-platform/ydb-dotnet-yc)**.
 
-### TableClient
-After you have driver instance, you can use it to create clients for different YDB services. The straightforward example of querying data may look similar to the following example:
+### QueryClient
+
+Example of using a query client to execute a simple query:
 
 ```c#
-// Create Ydb.Sdk.Table.TableClient using Driver instance.
-using var tableClient = new TableClient(driver, new TableClientConfig());
+// Create QueryClient using Driver instance.
+using var queryClient = new QueryService(driver);
 
-// Execute operation on arbitrary session with default retry policy
-var response = await tableClient.SessionExec(async session =>
-{
-    var query = @"
+var row = await queryClient.ReadRow(@"
         DECLARE $id AS Uint64;
 
         SELECT
@@ -63,31 +109,17 @@ var response = await tableClient.SessionExec(async session =>
             release_date
         FROM series
         WHERE series_id = $id;
-    ";
-
-    return await session.ExecuteDataQuery(
-        query: query,
-        parameters: new Dictionary<string, YdbValue>
-        {
-            { "$id", YdbValue.MakeUint64(id) }
-        },
-        // Begin serializable transaction and commit automatically after query execution
-        txControl: TxControl.BeginSerializableRW().Commit(),
-    );
-});
-
-response.Status.EnsureSuccess();
-
-var queryResponse = (ExecuteDataQueryResponse)response;
-var resultSet = queryResponse.Result.ResultSets[0];
+    ",
+    new Dictionary<string, YdbValue>
+    {
+        { "$id", YdbValue.MakeUint64(id) }
+    }
+);
 
-foreach (var row in resultSet.Rows)
-{
-    Console.WriteLine($"> Series, " +
-        $"series_id: {(ulong?)row["series_id"]}, " +
-        $"title: {(string?)row["title"]}, " +
-        $"release_date: {(DateTime?)row["release_date"]}");
-}
+Console.WriteLine($"> Series, " +
+    $"series_id: {(ulong?)row["series_id"]}, " +
+    $"title: {(string?)row["title"]}, " +
+    $"release_date: {(DateTime?)row["release_date"]}");
 ```
 
 ## Examples