子查询

——————————子查询—————————————-

———–将查询的结果作为子表，连表查询 
select * from StuInfo s1,(select * from StuMarks where Score >80)s2 where s1.StuID=s2.StuID AND s1.StuName=’李四’

———–将查询结果作为条件使用 
select * from StuInfo WHERE StuID>(select StuID from StuInfo where StuName=’王五’) 
———–将子查询作为临时表使用 
select s1.,s2 Score from StuInfo s1 left outer join (select from StuMarks where Subject=’HTML’) s2 on s1.StuID=s2.StuID 
———–将子查询作为列使用 (不建议使用) 
select s1.*,(select Score from StuMarks s2 where s1.StuID=s1.StuID and subject=’html’) Score from StuInfo s1 
———–使用in 和not in 完成子查询 
select StuName from StuInfo where StuID In (select StuID from StuMarks where Score >85 and Subject=’java’) 
———–使用exist 或not exist 完成子查询 
select * from StuInfo where exists (select * from StuMarks where StuMarks.StuID=StuInfo.StuID) 
———–使用some 、any、 all进行子查询 
——————–聚合函数—————————————————– 
—————使用compute 和compute by进行汇总 
———————-排序函数 
—————排序函数over([分组子句]排序子句[desc][asc]) 
—————排序子句order by 排序列，排序列……. 
—————分组排序 partition by 分组列，分组列

————————row__number()函数 
select row_number() over (order by Score DESC) AS 排名 
s1.StuName,s2.Score from StuInfo s1,StuMarks s2 where s1.StuID=s2.StuID and s2.Subject=’Java’

————————rank函数 
select rank() over (order by Score DESC) AS 排名 
s1.StuName,s2.Score from StuInfo s1,StuMarks s2 where s1.StuID=s2.StuID and s2.Subject=’Java’

————————DENSE_RANK()函数 
select dense_rank() over (order by Score DESC) AS 排名 
s1.StuName,s2.Score from StuInfo s1,StuMarks s2 where s1.StuID=s2.StuID and s2.Subject=’Java’ 
————————-使用partition by 分组子句 
select dense_rank() over (partition by s2.Subject order by Score DESC) AS 排名 
s1.StuName,s2.Subject,s2.Score from StuInfo s1,StuMarks s2 where s1.StuID=s2.StuID 
————————-公用表达式 
————–CTE的基本用法 
WITH expression_name[(column_name[,…n])] 
as 
(CTE_query_definition)

with StuInfo_Mark (StuID,StuName,Subject,Score) 
as 
( 
select s1.StuID,s1.StuName,s2.Subject, 
s2.Score from StuInfo s1,StuMarks s2 
where s1.StuID=s2.StuID 
) 
select * from StuInfo_Mark 
go