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分组sql语句条件

select * from table a where exists(select 1 from table where booksid=a.booksidgroup by booksidhaving max(datetime)=a.datetime)

分组是用来聚集汇总的,如求平均、求总和、求最大等你这个不需要分组,直接排序就可以了select name, date from table order by name asc, date desc 如果每组要按date的降序排列,也挺简单with t1 as (select name, max(date) md from table group by name,t2 as (select table.name name, table.date date, t1.md from table join t1 on table.name=t1.nameorder by t1.md)select name,date from t2

用分组,组内计数就可以了,意思就是根据字段a的取值进行分组,相同的为一组,在用count进行组内计数select a,count(*)from agroup by a

楼主你好,首先你要明白group by 是分组查询的意思 使用group by 关键字时,在select列表中可以指定的项目是有限制的,select语句中仅允许以下几项,1:被分组的列2:为每个分组返回一个值的表达式,例如用一个列明作为参数的聚合函数

distinct不要,后面加上group by就可以了.select count(a.deviceid) as count from 表 a where a.activationtime >= to_date('2011-03-24','yyyy-mm-dd') and a.activationtime < to_date('2011-03-24','yyyy-mm-dd')+1 and a.type = 2 and a.status = 1 group

--查所有的 就是重复的select CHI,count(aid) aid from tb where CHI in ('z','w','v') group by CHI--不重复的select CHI,count(distinct aid) aid from tb where CHI in ('z','w','v') group by CHI

select groupfield ,count(*) as numfrom tablexgroup by groupfield

select a,sum(qty) from table where c='t' group by a having sum(qty)>10 去掉不满足条件,用“having”

select * from Table_1 where num in(select a.num from (select num, count([STATE]) as stat0 from Table_1 where [STATE]>0 group by num) a inner join (select num,count(num) as num0 from Table_1 group by num) b on a.stat0=b.num0 and a.NUM=b.NUM)虽然我这个可以得出结果,但我觉得应该还有更好的思路.

B 例:select * from userdata group by userclass having userclass>3 即为选择级别大于3的所有组的用户并按组归类 注意一般情况下where是不可以和group by在同一个谓语select下使用的,你可以记成whereorder by,而 having group by .

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