sqlserver in 和 exist 子查询

1 in 子查询

1 use StudentManageDB
2 go
3 --select StudentName from Students 
4 --where StudentId=(select StudentId from scoreList where sqlServerDB>80)
5 select StudentName from Students 
6 where StudentId in (select StudentId from scoreList where sqlServerDB>80)

1 use StudentManageDB
2 go
3 select StudentId,StudentName from Students
4 where StudentId not in(select StudentId from scoreList)

2.exist 子查询

 1 use StudentManageDB
 2 go
 3 if exists(select * from scoreList where CSharp<60)
 4    print ‘本次考试内容较难‘
 5 else
 6    print ‘本次考试内容适中‘
 7 
 8 --NOT EXISTS的使用
 9 if not exists(select * from scoreList where CSharp<60)
10       print ‘本次考试内容适中‘
11 else
12       print ‘本次考试内容较难‘