进行声明

SQL Server 入门

John MacKintosh

Instructor

变量

SELECT * 
FROM artist 
WHERE name = 'AC/DC';

现在将查询改为另一位艺人：

SELECT * 
FROM artist 
WHERE name = 'U2';

为避免重复，创建一个变量：

SELECT * 
FROM artist 
WHERE name = @my_artist;

DECLARE

DECLARE @

整数变量：

DECLARE @test_int INT

Varchar 变量：

DECLARE @my_artist VARCHAR(100)

SET

整数变量：

DECLARE @test_int INT

SET @test_int = 5

为 @my_artist 赋值：

DECLARE @my_artist  varchar(100)

SET @my_artist = 'AC/DC'

DECLARE @my_artist varchar(100)
DECLARE @my_album varchar(300);

SET @my_artist = 'AC/DC'
SET @my_album  = 'Let There Be Rock' ;

SELECT --
FROM --
WHERE artist = @my_artist
AND album = @my_album;

DECLARE @my_artist varchar(100)
DECLARE @my_album varchar(300);

SET @my_artist = 'U2'
SET @my_album  = 'Pop' ;

SELECT --
FROM --
WHERE artist = @my_artist
AND album = @my_album;

临时表

SELECT 
  col1, 
  col2, 
  col3 INTO #my_temp_table
FROM my_existing_table 
WHERE 
  -- Conditions

#my_temp_table 在连接或会话结束前存在

-- 手动删除表
DROP TABLE #my_temp_table

来声明一些变量！

SQL Server 入门