复合主键在表变量在存储过程

Question

我是新来的存储过程，并试图添加一个复合主键到表变量。

DECLARE @statistictemp TABLE (
    MajorName  VARCHAR(50) NOT NULL, 
    SubName  VARCHAR(50) NOT NULL, 
    DetailedName VARCHAR(50) NOT NULL, 
    UniversityID SMALLINT NOT NULL, 
    StatisticValue DECIMAL(9,3) 
); 

ALTER TABLE @statistictemp 
ADD CONSTRAINT pk_statistictemp 
PRIMARY KEY (MajorName, SubName, DetailedName, UniversityID); 

我得到的ALTER TABLE @statistictemp一个错误说

Incorrect syntax near '@statistictemp'. Expecting ID, QUOTED_ID, or '.'.

我在做什么错在这里？如何将复合主键添加到表变量？

Answer 1

你可以这样说：

DECLARE @statistictemp TABLE (
    MajorName  VARCHAR(50) NOT NULL, 
    SubName  VARCHAR(50) NOT NULL, 
    DetailedName VARCHAR(50) NOT NULL, 
    UniversityID SMALLINT NOT NULL, 
    StatisticValue DECIMAL(9,3), 
    PRIMARY KEY (MajorName, SubName, DetailedName, UniversityID) 
); 

您可以测试该主键约束的工作原理是试图插入重复： 例如，

INSERT INTO @statistictemp(MajorName, SubName, DetailedName, UniversityID) SELECT 'a','b','c',1 
INSERT INTO @statistictemp(MajorName, SubName, DetailedName, UniversityID) SELECT 'a','b','c',1 

第二条语句将抛出一个错误：

Msg 2627, Level 14, State 1, Line 13
Violation of PRIMARY KEY constraint 'PK_#1EA48E8_B595483D208CD6FA'. Cannot insert duplicate key in object 'dbo.@statistictemp'.
The statement has been terminated.