——————————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