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group By Count

select count(*) num,sid into #a from person group by sid select count(*) from #a 或者 select count(*) from (select count(*) num,sid from person group by sid )

如表为test,数据如下: id grade 1 100 1 80 2 90 2 80 3 90 此时,可用count可求每个id在表中的个数,可用如下sql语句 select id,count(*) as counts from test group by id;结果如下: id counts 1 2 2 2 3 1 但group by还用另一种用法,就是...

还可以和很多啊 sum() avg() min() max() 等 这类都叫聚合函数 还可以去重,如果有重复数据的话,可以用group by,打个比方 如果表里有一列字段叫id id 1 1 2 2 select id from 表名 group by id 这样得到的结果只有1和2 这个用法类似于distinct...

--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

create table t ( id int, a int, b int ) insert into t values(1,101,1) insert into t values(2,102,1) insert into t values(3,101,2) insert into t values(4,102,2) insert into t values(5,101,1) insert into t values(6,102,3) insert...

看样子像是access啊? access的话: select t.id,count(t.随访号) as 随访次数 from(select id,随访号 from 表1 group by id,随访号) as t group by t.id其他数据库的话: select id,count(distinct 随访号) as 随访次数 from 表1 group by id

看不出来的stuid字段里是否一部分是空格一部分空串,你先用下面语句检查一下select decode(lc,'','',‘ ’,999999,0),zid from zuowei2 另外where zuowei2.stuid like' '能否换成where trim(zuowei2.stuid) is null试一下?

加个where 条件不行么,where status 0 如果不行的话,就写子查询, 先筛选where status 0 再group by

1、查出表中重复列的数据:select a,count(*) from table group by a having count(*)>1 2、查重复次数最多的列:select a,num from (select a,count(*) num from table group by a having count(*)>1)order by num desc 此外,还有 1、查询一个...

group by a,b以a,b作为分组,就是a和b相同的只显示一条数据,可能有很多条a,b相同的,所以给他统计count(*)相同的个数,并且将结果以count(*) 降序排列order by count(*) desc,我不知道这语法是否有问题:如果能够改为如下,我觉得不会有问题的...

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