无法在 SQL Server 2005 中删除约束，“无法删除约束。请参阅以前的错误”
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Unable to drop constraint in SQL server 2005, "Could not drop constraint. See previous errors"
提问by DannykPowell
I'm trying to drop a constraint on a DB table, something like:
我正在尝试删除数据库表上的约束，例如：
ALTER TABLE MyTable drop CONSTRAINT FK_MyTable_AnotherTable
But the execution just runs and runs. If I stop it I see:
但执行只是运行和运行。如果我停止它，我会看到：
Msg 3727, Level 16, State 0, Line 2
Could not drop constraint. See previous errors.
Web search throws up various pages but note that the constraint is properly named and I am trying to remove it using the correct name
网络搜索会抛出各种页面，但请注意约束已正确命名，我正在尝试使用正确的名称将其删除
采纳答案by DannykPowell
Found a way to sort this, although I don't understand why it was necessary.
找到了一种对此进行排序的方法，尽管我不明白为什么需要这样做。
Have been able to drop the constraint by disabling it first:
已经能够通过首先禁用它来删除约束：
ALTER MyTable NOCHECK CONSTRAINT FK_MyTable_AnotherTable
The drop then completes fine
然后下降完成
Would still welcome any comments on the reason why this is necessary
仍然欢迎任何评论为什么这是必要的
回答by Zeeshan Ajmal
I was having the same issue on SQL Server 2008 R2, I solved my problem with below line hopefully it will work for someone else as well :)
我在SQL Server 2008 R2上遇到了同样的问题，我用下面的代码解决了我的问题，希望它也适用于其他人:)
Alter Table [Table Name]
DROP Column [Column Name]
回答by Andomar
Verify that you've not already dropped the constraint, like:
验证您尚未删除约束，例如：
SELECT OBJECT_ID('FK_MyTable_AnotherTable')
If this returns null, your constraint no longer exists. That would explain the error message.
如果返回null，则您的约束不再存在。这将解释错误消息。
回答by flam3
I had same problem.
我有同样的问题。
The reason was that I made a mistake in my cursor statement, which was iterating some constraint I was to drop. So this error occurred when the constraint was actually removed in the same transaction. Then I did a rollback and checked if it existed: it did (of course, after rollback!).
原因是我在游标语句中犯了一个错误，它迭代了我要删除的一些约束。所以这个错误发生在约束在同一个事务中被实际删除的时候。然后我做了一个回滚并检查它是否存在：它确实存在（当然，在回滚之后！）。
Check if it really exists at the moment of dropping.
在掉落的那一刻检查它是否真的存在。
