背景： @H_301_2@我们有一个使用ef-migrations的项目,其中包含长时间开发中创建的多个(read〜60)迁移.当然这些迁移也涉及到：

@H_301_2@> drop constraints1,2
>创建触发器

@H_301_2@当我们跑步时,都是独角兽和彩虹

Update-Database

@H_301_2@因为每个迁移作为单独的批次运行.但是使用这些迁移创建sql脚本时

Update-Database -Script

@H_301_2@我们遇到了一些问题,如下所述：

@H_301_2@问题1：

@H_301_2@在多个迁移文件中删除多个约束时,EF生成的脚本往往会重新声明其用于删除的变量.这是因为它确保了同一迁移文件中的变量名称的唯一性,但是在更改文件时,会重置计数器,从而重叠名称.

@H_301_2@问题二：

@H_301_2@sql强制CREATE TRIGGER始终是批处理中的第一个语句.当脚本生成时,EF忽略sql(“CREATE TRIGGER …”)的内容;因此不特别对待它.因此,该语句可能出现在脚本文件的中间,并出错.

@H_301_2@解决方案：(或者我们以为！)

@H_301_2@这两个问题的常见/常识解决方案是在正确的位置插入开始/结束sql批处理.手动这样做会使我成为一个非常有钱的人,所以这不是一个有效的解决方案.

@H_301_2@相反,我们使用了technique provided by @DavidSette.创建一个从sqlServerMigrationsqlGenerator继承的新的BatchsqlServerMigrationsqlGenerator,它有效地覆盖了dropColumnOperation和sqlOperation,然后强制围绕敏感的一个GO语句：

protected override void Generate (System.Data.Entity.Migrations.Model.DropColumnOperation dropColumnOperation)
{
    base.Generate(dropColumnOperation);
    Statement("GO");
}

@H_301_2@嘘嘘：

@H_301_2@此解决方案中断运行Update-Database而不使用-Script标志,并显示以下错误：

System.Data.sqlClient.sqlException (0x80131904): Could not find stored procedure 'GO'.

@H_301_2@这是由我们的定制生成器添加的.现在我不知道为什么,但应该有一个很好的理由EF不认识GO！

@H_301_2@更多信息：

@H_301_2@> Migrations: Duplicate @var0 variables in script that drops two constraints
> The variable name ‘@number’ has already been declared
> How can I override SQL scripts generated by MigratorScriptingDecorator
> Entity Framework Migrations: Including Go statement only in -Script output

@H_301_2@全错误：

Applying code-based migration: 201205181406363_AddTriggerForOverlap.
GO
System.Data.sqlClient.sqlException (0x80131904): Could not find stored procedure 'GO'.
    at System.Data.sqlClient.sqlConnection.OnError(sqlException exception,Boolean breakConnection,Action`1 wrapCloseInAction)
    at System.Data.sqlClient.sqlInternalConnection.OnError(sqlException exception,Action`1 wrapCloseInAction)
    at System.Data.sqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj,Boolean callerHasConnectionLock,Boolean asyncClose)
    at System.Data.sqlClient.TdsParser.TryRun(RunBehavior runBehavior,sqlCommand cmdHandler,sqlDataReader dataStream,BulkCopySimpleResultSet bulkCopyHandler,TdsParserStateObject stateObj,Boolean& dataReady)
    at System.Data.sqlClient.sqlCommand.RunExecuteNonQueryTds(String methodName,Boolean async,Int32 timeout)
    at System.Data.sqlClient.sqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion,String methodName,Boolean sendToPipe,Int32 timeout,Boolean asyncWrite)
    at System.Data.sqlClient.sqlCommand.ExecuteNonQuery()
    at System.Data.Entity.Migrations.DbMigrator.Executesql(DbTransaction transaction,MigrationStatement migrationStatement)
    at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.Executesql(DbTransaction transaction,MigrationStatement migrationStatement)
    at System.Data.Entity.Migrations.DbMigrator.ExecuteStatements(IEnumerable`1 migrationStatements)
    at System.Data.Entity.Migrations.Infrastructure.MigratorBase.ExecuteStatements(IEnumerable`1 migrationStatements)
    at System.Data.Entity.Migrations.DbMigrator.ExecuteOperations(String migrationId,XDocument targetModel,IEnumerable`1 operations,Boolean downgrading,Boolean auto)
    at System.Data.Entity.Migrations.DbMigrator.ApplyMigration(DbMigration migration,DbMigration lastMigration)
    at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.ApplyMigration(DbMigration migration,DbMigration lastMigration)
    at System.Data.Entity.Migrations.DbMigrator.Upgrade(IEnumerable`1 pendingMigrations,String targetMigrationId,String lastMigrationId)
    at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.Upgrade(IEnumerable`1 pendingMigrations,String lastMigrationId)
    at System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration)
    at System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update(String targetMigration)
    at System.Data.Entity.Migrations.Design.ToolingFacade.UpdateRunner.RunCore()
    at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.Run()
ClientConnectionId:ac53af4b-1f9b-4849-a0da-9eb33b836caf
Could not find stored procedure 'GO'.

@H_301_2@所以基本上修复脚本打破了一个重要的命令.请帮我决定哪一个是两个罪恶中的较小者！