Question

聚合函数和GROUP BY的问题

一个表有id,name,sex,class等字段。
SELECT count(*) AS num,id,name,sex,class
FROM table
where name LIKE '%a%'
GROUP BY id
ORDER BY id DESC

会出错，将GROUP BY id 改成GROUP BY id,name,sex,class可成功，但查出来的count(*)不符合我期望的值，比如说表中有a,ab,abc.应该查出count(*)为3，但这样只为1。求高手指点。另如果分2次查，存储过程怎么写？

Answer 1

select a.id,a.name,a.sex,a.class,b.num from table a,
(select id,count(*) as num from table
where name LIKE '%a%'
GROUP BY id) b
where a.id=b.id
order by a.id desc

Answer 2

select a.id,a.name,a.sex,a.class,b.num from table a,
(select id,count(*) as num from table
where name LIKE '%a%'
GROUP BY id) b
where a.id=b.id
order by a.id desc.
聚合函数对一组值执行计算并返回单一的值。聚合函数忽略空值。聚合函数经常与 SELECT 语句的 GROUP BY 子句一同使用。

Answer 3

select T.num,A.* from table A,(SELECT id,count(*) AS num from table where where name LIKE '%a%' group by id) B where A.id=B.id order by id desc