Question

如果我按如下方式检查列的存在，在添加之前，我将如何处理UNIQUE约束的等效项？

IF NOT EXISTS (SELECT * FROM sys.columns WHERE object_id=OBJECT_ID('[Table]') AND [Name]='Column')
    ALTER TABLE [Table] 
    ADD 
    [Column] varchar(500)

Answer 1

对于约束FK_myTable（SQL 2000）：

if not exists ( select *
    from sysconstraints sc
    inner join sysobjects tbl on sc.id = tbl.id
    inner join sysobjects con on sc.constid = con.id
    where tbl.name = 'myTable' and con.name = 'FK_myTable' )

Answer 2

从sys.objects中选择*，其中type ='uq'，parent_object_id = OBJECT_ID（'[Table]'）

检查表上的约束

2 个答案: