SQL里变量的声明以及常用函数举例

知识点：

①声明变量：DECLARE  关键字

②循环语句：WHILE ... 

                        BEGIN ...

                       END 

③数据类型转换：CAST()函数

应用举例：

初始化脚本：

CREATE TABLE [dbo].[TEST]( [ID] [int] IDENTITY(1,1) NOT NULL, [TID] [int] NULL, [Discription] [nvarchar](200) NULL ) --测试数据 DELETE FROM TEST INSERT INTO TEST (TID,Discription)VALUES (1,'记录1-1') INSERT INTO TEST (TID,Discription)VALUES (1,'记录1-2') INSERT INTO TEST (TID,Discription)VALUES (1,'记录1-3') INSERT INTO TEST (TID,Discription)VALUES (1,'记录1-4') INSERT INTO TEST (TID,Discription)VALUES (1,'记录1-5') INSERT INTO TEST (TID,Discription)VALUES (2,'记录2-1') INSERT INTO TEST (TID,Discription)VALUES (2,'记录2-2') INSERT INTO TEST (TID,Discription)VALUES (2,'记录2-3') SELECT * FROM TEST
演练脚本：

DECLARE @startIndex INT,@endIndex INT,@discription NVARCHAR(100); SELECT @startIndex= MIN(ID)FROM TEST;--最小记录ID SELECT @endIndex= MAX(ID)FROM TEST;--最大记录ID WHILE @startIndex <@endIndex BEGIN Select @discription=('第'+CAST(ID as NVARCHAR(100))+'行记录：'+CAST(TID as NVARCHAR(100))+'.'+Discription) FROM TEST WHERE ID=@startIndex; PRINT(@discription); SELECT @startIndex=@startIndex+1--当前记录加1 END