Sql server 在使用sql脚本添加外键之前检查外键

我有一个向表中添加外键的SQL脚本，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;

有时表已经有这个外键，所以从ManagementStudio运行时会显示错误。在应用密钥之前，是否可以添加查询以检查密钥是否存在？有更好的方法吗？这必须适用于MS SQL 2005和2008。

使用该函数测试是否存在

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;

---

您可以通过查看以下内容来检查外键的存在：

---

这么简单。为什么其他人都发布如此复杂的回复？

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