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hAving Count

对由sum、count或其它集合函数运算结果的输出进行限制 having count(学号)指的是 学生数目( 大于等于)数值 create TABLE Table1 ( ID int identity(1,1) primary key NOT NULL, classid int, sex varchar(10), age int, ) --添加测试数据 In...

having表示条件,用在聚合函数中,意思呢和where是一样的,只是where不能和聚合函数一起使用

select id, count(*) from table a where ... group by id having count(*)>2 -- 以id分组统计,查询分组后数量大于2的id和数量。

出现了having说明用到了聚合函数,having用来约束聚合后的内容,举个例子 selelct id,sum(value) from table where id > 5 group by value having count(value)>3 where只能约束id>5的行,但是之后结果被聚合,行被合并,where就没用了,我们要...

--1,查询hm有重复的记录select hm,count(*) from a group by hm having count(*)>1--2,查询hm和xm都有重复select hm,xm count(*) from a group by hm,xm having count(*)>1

做法:select * from user_num group by user HAVING sum(num)>10 ; 注意:一个HAVING子句最多只能包含40个表达式,HAVING子句的表达式之间可以用AND和OR分割。

61=C或D 62=C SELECT Sno , AVG(Grade) FROM SC GROUP BY Sno HAVING COUNT(Sno)>1;

select id, count(*) from table a where ... group by id having count(*)>2 -- 以id分组统计,查询分组后数量大于2的id和数量。

having count(*)>5 指只显示分组後组内成员数大於5的资料 如有表A (col1,col2),值如下 col1 col2 A 1 A 10 A 5 A 6 A 7 A 2 B 4 B 9 select col1,sum(col2) as scol2 from A group by A having count(*) > 5; 则结果只会显示A的汇总,因为只是A...

GROUP BY 学号表示的是以学号来进行分类,HAVING COUNT(*)>=3 表示的是其选课门数要至少为3门!

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