局部變量

 1 use StudentManageDB
 2 go
 3 --聲明學號變量
 4 declare @stuid int,@stuname varchar(20)
 5 
 6 --查詢李銘的信息
 7 set @stuname=‘李銘‘
 8 select StudentId,StudentName,Gender,StudentIdNo from Students
 9 where StudentName=@stuname
10 
11 --查詢李銘的學號
12 select @stuId=StudentId from Students where StudentName=@stuname
 

13 
14 --查詢與李銘學號相鄰的學員
15 select StudentId,StudentName,Gender,StudentIdNo from Students
16 where StudentId=(@stuId+1) or StudentId=(@stuId-1)

set與select比較

1     declare @stuAddress nvarchar(100) , @stuName nvarchar(100)
2     --set @stuAddress=‘天津‘, @stuName=‘張三‘                            --不允許這樣賦值
3
 
     select @stuaddress=‘天津‘, @stuName=‘王小虎‘             --允許
4 
5     --set @stuAddress = (select StudentAddress from Students)  --不允許
6     select @stuAddress = StudentAddress from Students    --得到最後一個
7     set @stuAddress = (select StudentAddress from Students where 1<0) --NULL值
8     select @stuAddress
 
 =  StudentAddress from Students where 1<0        --保持原值

全局變量

1 PRINT  ‘服務器的名稱: ‘ + @@SERVERNAME  
2 PRINT ‘SQL Server的版本‘ + @@VERSION 
3   
4 SELECT  @@SERVERNAME  AS  ‘服務器名稱‘
5 SELECT  @@VERSION  AS  ‘SQL Server的版本‘ 

 1 use StudentManageDB
 2 go
 3 --插入學員信息
 4 insert into Students (StudentName,Gender,Age,Birthday,StudentIdNo,
 5 PhoneNumber,StudentAddress,ClassId)
 6 values(‘王小欣‘,‘男‘,28,‘1988-08-07‘,120223198808071111,
 7 ‘022-22222222‘,‘天津市南開區‘,10)
 8 
 9 
10 --獲取最後一條SQL語句的執行錯誤號
11 print @@error

T-SQL 局部變量和全局變量