Question

我的sql server中有一个现有的表，我想在该表的列上添加一个主键。我知道语法是：

ALTER TABLE PromotionBenefit  
ADD CONSTRAINT PK_PromotionBenefit2 PRIMARY KEY CLUSTERED (PromotionBenefitCode);  
GO

问题是该列已经有一个主键（相同的约束名称）。所以它抛出一个错误。那样就好。我想知道是否可以在我的查询中添加IF NOT Exists，这样就不会抛出任何错误。

使用什么语法？

编辑：有没有办法使用这种方式：IF NOT EXISTS ....创建PRIMARY KEY CLUSTERED而不是像上面所示改变表？可以这样做：

IF NOT EXISTS (SELECT * FROM sys.indexes WHERE object_id = OBJECT_ID(N'[dbo].[PromotionBenefit]') AND name = N'idx_EventCode')
CREATE NONCLUSTERED INDEX [idx_EventCode] ON [dbo].[PromotionBenefit]
(
    [EventCode] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 80) ON [PRIMARY]
GO

Answer 1

您必须执行以下操作：

DECLARE @IsPrimary INT

SELECT @IsPrimary=COUNT(1)
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE OBJECTPROPERTY(OBJECT_ID(CONSTRAINT_SCHEMA + '.' + QUOTENAME(CONSTRAINT_NAME)), 'IsPrimaryKey') = 1
AND TABLE_NAME = 'PromotionBenefit'

IF @IsPrimary>0
BEGIN
    SELECT 'Table already have Primary Key'
END
ELSE
BEGIN
    ALTER TABLE PromotionBenefit  
    ADD CONSTRAINT PK_PromotionBenefit2 PRIMARY KEY CLUSTERED (PromotionBenefitCode);  
    GO
END

如果你认为，那就不要比试试这个：

IF NOT EXISTS(
SELECT 1
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE OBJECTPROPERTY(OBJECT_ID(CONSTRAINT_SCHEMA + '.' + QUOTENAME(CONSTRAINT_NAME)), 'IsPrimaryKey') = 1
AND TABLE_NAME = 'PromotionBenefit')
BEGIN
    ALTER TABLE PromotionBenefit  
    ADD CONSTRAINT PK_PromotionBenefit2 PRIMARY KEY CLUSTERED (PromotionBenefitCode);  
    GO
END

试试这个：

IF NOT EXISTS(SELECT 1 FROM sys.objects WHERE type = 'PK' AND  parent_object_id = OBJECT_ID ('PromotionBenefit'))
BEGIN
    ALTER TABLE PromotionBenefit  
    ADD CONSTRAINT PK_PromotionBenefit2 PRIMARY KEY CLUSTERED (PromotionBenefitCode)
END

希望它对你有所帮助。

Answer 2

一种做预期的简短方法：

IF OBJECT_ID('idx_EventCode') is null
   CREATE NONCLUSTERED INDEX [idx_EventCode] ON [dbo].[PromotionBenefit] 
   ( [EventCode] ASC) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, 
     DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, 
     FILLFACTOR = 80) ON [PRIMARY]
GO

OBJECT_ID可与SqlServer中的任何对象一起使用，我还使用它来检测表，视图，存储过程的存在...

使用主键上的不存在

2 个答案: