Question

我有一张名为Card的表，我正在使用名为Card_shadow的影子表进行审核。每当插入，更新或删除行时，影子表都会通过卡表上的插入，更新和删除触发器获取新行。

现在是时候在卡表中添加一列了。在我看来，我需要编写一些可重复的SQL，它可以在现有的事务中运行，该事务将： 1.将列添加到卡表和影子表中，然后 2.更改触发器以使用新列

我试图通过这里的代码来做到这一点：

private string addVoidColumn(SqlConnection db, SqlTransaction transaction)
{
    string sql = @" IF EXISTS(  SELECT * 
                                FROM INFORMATION_SCHEMA.COLUMNS 
                                WHERE TABLE_NAME = 'Card' AND  COLUMN_NAME = 'c_void_d')
                    ALTER TABLE [dbo].[Card] DROP COLUMN [c_void_d]

                    IF EXISTS(  SELECT * 
                                FROM INFORMATION_SCHEMA.COLUMNS 
                                WHERE TABLE_NAME = 'Card_shadow' AND  COLUMN_NAME = 'c_void_d')
                    ALTER TABLE [dbo].[Card_shadow] DROP COLUMN [c_void_d]

                    ALTER TABLE dbo.Card 
                    ADD c_void_d datetime NULL

                    ALTER TABLE dbo.Card_shadow
                    ADD c_void_d datetime NULL";
    executeNonQuery(sql, db, transaction);

    sql =         @"ALTER TRIGGER [dbo].[tr_Card_Update] 
                    ON [dbo].[Card] FOR UPDATE AS 
                    INSERT INTO dbo.Card_shadow(c_id_n,c_void_d,AuditAction) 
                    SELECT c_id_n,c_void_d,'U' 
                    FROM Inserted";
    executeNonQuery(sql, db, transaction);

    sql =         @"ALTER TRIGGER [dbo].[tr_Card_Insert] 
                    ON [dbo].[Card] FOR INSERT AS 
                    INSERT INTO dbo.Card_shadow(c_id_n,c_void_d,AuditAction) 
                    SELECT c_id_n,c_void_d,'U' 
                    FROM Inserted";
    executeNonQuery(sql, db, transaction);

    sql =         @"ALTER TRIGGER [dbo].[tr_Card_Delete] 
                    ON [dbo].[Card] FOR DELETE AS 
                    INSERT INTO dbo.Card_shadow(c_id_n,c_void_d,AuditAction) 
                    SELECT c_id_n,c_void_d,'U' 
                    FROM Deleted";
    executeNonQuery(sql, db, transaction);
}

private static void executeNonQuery(string sql, SqlConnection db, SqlTransaction transaction) { executeNonQuery(sql, db, transaction, 300); }
private static void executeNonQuery(string sql, SqlConnection db, SqlTransaction transaction, int timeoutInSeconds)
{
    using(SqlCommand cmd = new SqlCommand(sql,db,transaction))
    {
        cmd.CommandTimeout = timeoutInSeconds;
        cmd.ExecuteNonQuery();
    }
}

此方法传递一个打开的连接和一个现有的事务。当调用代码提交事务时，它运行正常并且不会抛出异常，但触发器不会被更改。这就是我难倒的地方。我怀疑在添加触发器之前需要提交列添加，但我不确定。有什么想法吗？

Answer 1

不确定自己，但是当你改变桌子时，触发器被塞满了，可能被认为是无效的东西。

alter table命令中有一个参数用于禁用和启用触发器所以也许禁用触发器alter table，alter trigger，enable triggers将是一个好人。

鉴于你正在做什么，虽然我只是放下触发器然后再创建它......

更改触发器以使用在包含触发器alter的同一事务中创建的列

1 个答案: