Transact-SQL transaction rollback not working properly when using GO commands

Question

I have a migration script written in Transact-SQL which is using transactions in order to have a proper rollback if something goes wrong during the execution. Unfortunately, thi

Answer 1

Some errors roll back the transaction. Don't bother figuring out which ones, because there's no simple rule.

A multi-batch script should have a single error handler scope that rolls back the transaction on error, and commits at the end. In TSQL you can do this with dynamic sql, eg

BEGIN TRANSACTION
BEGIN TRY

    EXEC('
    -- Create a table with two nullable columns
    CREATE TABLE [dbo].[t1](
        [id] [nvarchar](36) NULL,
        [name] [nvarchar](36) NULL
    )
    ')

    EXEC('
    -- add one row having one NULL column
    INSERT INTO [dbo].[t1] VALUES(NEWID(), NULL)
    ')
    -- set one column as NOT NULLABLE
    -- this fails because of the previous insert
    EXEC('
    ALTER TABLE [dbo].[t1] ALTER COLUMN [name] [nvarchar](36) NOT NULL
    ')

    EXEC('
    -- create a table as next action, so that we can test whether the rollback happened properly
    CREATE TABLE [dbo].[t2](
        [id] [nvarchar](36) NOT NULL
    )
    ')

    COMMIT TRANSACTION;
END TRY
BEGIN CATCH
  IF @@TRANCOUNT > 0 ROLLBACK;
  THROW;
END CATCH

With SQLCMD you can use the -b option to abort the script on error.