2013-10-02 98 views
0

第二个ALTER TABLECHECK CONSTRAINT是否在IF (NOT) EXISTS中,以便该脚本可以重复执行?SQL检查是否运行了“CHECK CONSTRAINT”?

IF NOT EXISTS (
    SELECT * FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS 
    WHERE CONSTRAINT_NAME ='fk_RoleId' 
) 
BEGIN 
    ALTER TABLE [dbo].[webpages_UsersInRoles] WITH CHECK ADD CONSTRAINT [fk_RoleId] FOREIGN KEY([RoleId]) 
    REFERENCES [dbo].[webpages_Roles] ([RoleId]) 
END 
GO 

-- Put me in an IF ...() BEGIN ... END? 
ALTER TABLE [dbo].[webpages_UsersInRoles] CHECK CONSTRAINT [fk_RoleId] 
GO 

它不会引起任何错误,但如果它应该是在IF条款,你怎么测试,如果它已经跑了(什么可以如果包含)?

+0

第二步是多余的。请参阅http://stackoverflow.com/questions/529941/whats-the-difference-between-with-check-add-constraint-followed-by-check-constr –

回答

1

如果你想有一个检查(这不是必要的),sys.foreign_keys有一列is_not_trusted

FOREIGN KEY约束还没有被系统验证。