Question

我有一个SQL脚本，它将一个外键添加到表中，如下所示。

ALTER TABLE [security].[Pages] WITH NOCHECK
ADD CONSTRAINT [FK_Pages_PageClasses] FOREIGN KEY ([PageClassId]) REFERENCES [security].[PageClasses]([PageClassId]) ON DELETE NO ACTION ON UPDATE NO ACTION;

有时表已有此外键，因此从Management Studio运行时会显示错误。是否可以在应用密钥之前添加查询以检查密钥是否存在？有一个更好的方法吗？这必须适用于MS SQL 2005和2008。

Answer 1

使用OBJECT_ID功能测试是否存在。

IF OBJECT_ID('[security].[FK_Pages_PageClasses]') IS NULL
    ALTER TABLE [security].[Pages] WITH NOCHECK
        ADD CONSTRAINT [FK_Pages_PageClasses] FOREIGN KEY ([PageClassId]) REFERENCES [security].[PageClasses]([PageClassId]) ON DELETE NO ACTION ON UPDATE NO ACTION;

Answer 2

您可以通过查看sys.foreign_keys object catalog view：

来检查是否存在外键

IF NOT EXISTS(SELECT * FROM sys.foreign_keys WHERE object_id = object_id(N'[Security].[FK_Pages_PageClasses]') and parent_object_id = object_id(N'[Security].[Pages]'))
BEGIN
    ALTER TABLE [security].[Pages] WITH NOCHECK
    ADD CONSTRAINT [FK_Pages_PageClasses] FOREIGN KEY ([PageClassId]) REFERENCES [security].[PageClasses]([PageClassId]) ON DELETE NO ACTION ON UPDATE NO ACTION;
END

在使用sql脚本添加外键之前检查外键

2 个答案: