Merge pull request #6 from nblumhardt/pgup

Apply -> Update

Author: nblumhardt

README.md

@@ -12,17 +12,19 @@ Piggy is a simple command-line tool for managing schema and data changes to Post
 
 Piggy is available for Windows, macOS and Linux from [the releases page](https://github.com/datalust/piggy/releases). Download the MSI or archive file for [your platform](https://docs.microsoft.com/en-us/dotnet/core/rid-catalog). If your platform of choice isn't listed, please [raise an issue here](https://github.com/datalust/piggy/issues) so that we can add it.
 
-### Organizing change scripts
+### Workflow
 
-Your `.sql` files should be named so that they will sort lexicographically in the order they need to be executed:
+To manage database updates with Piggy, write SQL scripts to make changes, rather than applying changes directly.
+
+Organize change scripts on the file system under a _script root_ directory. Name files so that they sort lexicographically in the order in which they need to be executed:
 
 ```
 001-create-schema.sql
 002-create-users-table.sql
 003-...
 ```
 
-If the scripts are arranged in subfolders, these can be ordered as well:
+If the scripts are arranged in subdirectories, these must be ordered by name as well:
 
 ```
 v1/
@@ -33,21 +35,21 @@ v2/
   001-rename-users-table.sql
 ```
 
-Each script is just regular SQL with any DDL or DML statements required to make a change to the database. Over time, as your application grows, create new scripts to move the database forwards.
-
-### Applying scripts
-
-Scripts must be applied starting from a _script root_. Piggy searches for `.sql` files and generates script names like `/v1/001-create-schema.sql` using each script's filename relative to the script root. These relative filenames are checked against the change log table to determine which of them need to be run.
+Piggy enumerates `.sql` files and generates names like `/v1/001-create-schema.sql` using each script's filename relative to the script root. These relative names are checked against the change log table to determine which of them need to be run.
 
-The script root is specified with `-s`. Other parameters identify the database server host, the database name, username and password:
+To bring a database up to date, run `piggy up`, providing the script root, host, database name, username and password:
 
 ```
-piggy apply -s <scripts> -h <host> -d <database> -u <username> -p <password>
+piggy up -s <scripts> -h <host> -d <database> -u <username> -p <password>
 ```
 
 If the database does not exist, Piggy will create it using sensible defaults. To opt out of this behavior, add the `--no-create` flag.
 
-For more detailed usage information, run `piggy help apply`; to see all available commands run `piggy help`.
+Over time, as your application grows, create new scripts to move the database forwards - don't edit the existing ones, since they've already been applied and will be ignored by Piggy.
+
+Piggy can be used to update from any previous schema version to the current one: scripts that have already been run on a database are ignored, so only necessary scripts are applied.
+
+For more detailed usage information, run `piggy help up`; to see all available commands run `piggy help`.
 
 ### Transactions
 
@@ -73,9 +75,9 @@ Values are inserted using pure text substitution: no escaping or other processin
 Variables are supplied on the command-line with the `-v` flag:
 
 ```
-piggy apply ... -v schema=myapp -v admin=myuser
+piggy up ... -v schema=myapp -v admin=myuser
 ```
 
 ### Change log
 
-The change log is stored in the target database in `piggy.changes`. The `piggy log` command can be used to view applied change scripts.
+The change log is stored in the target database in `piggy.changes`. The `piggy log` command is used to view applied change scripts.

…alust.Piggy/Cli/Commands/ApplyCommand.cs …lust.Piggy/Cli/Commands/UpdateCommand.cssrc/Datalust.Piggy/Cli/Commands/ApplyCommand.cs renamed to src/Datalust.Piggy/Cli/Commands/UpdateCommand.cs src/Datalust.Piggy/Cli/Commands/ApplyCommand.cs renamed to src/Datalust.Piggy/Cli/Commands/UpdateCommand.cs

@@ -5,8 +5,8 @@
 
 namespace Datalust.Piggy.Cli.Commands
 {
-    [Command("apply", "Apply a set of database change scripts")]
-    class ApplyCommand : Command
+    [Command("up", "Bring a database up to date")]
+    class UpdateCommand : Command
     {
         readonly DefineVariablesFeature _defineVariablesFeature;
         readonly UsernamePasswordFeature _usernamePasswordFeature;
@@ -16,7 +16,7 @@ class ApplyCommand : Command
         string _scriptRoot;
         bool _createIfMissing = true;
 
-        public ApplyCommand()
+        public UpdateCommand()
         {
             _databaseFeature = Enable<DatabaseFeature>();
             _usernamePasswordFeature = Enable<UsernamePasswordFeature>();
@@ -44,7 +44,7 @@ protected override int Run()
 
             try
             {
-                ApplySession.ApplyChangeScripts(
+                UpdateSession.ApplyChangeScripts(
                     _databaseFeature.Host, _databaseFeature.Database, _usernamePasswordFeature.Username, _usernamePasswordFeature.Password,
                     _createIfMissing, _scriptRoot, _defineVariablesFeature.Variables);
 

…Datalust.Piggy/Apply/ChangeScriptFile.cs …atalust.Piggy/Update/ChangeScriptFile.cssrc/Datalust.Piggy/Apply/ChangeScriptFile.cs renamed to src/Datalust.Piggy/Update/ChangeScriptFile.cs src/Datalust.Piggy/Apply/ChangeScriptFile.cs renamed to src/Datalust.Piggy/Update/ChangeScriptFile.cs

@@ -10,7 +10,7 @@
 
 namespace Datalust.Piggy.Apply
 {
-    static class ApplySession
+    static class UpdateSession
     {
         public static void ApplyChangeScripts(string host, string database, string username, string password,
             bool createIfMissing, string scriptRoot, IReadOnlyDictionary<string, string> variables)