Question

寻一个SQL语句 统计 另一表的数据 表1 p_cond ID 1 2 3 4 表2 p_cond_han p_cond

Answer 1

select a.id,isnull(b.counts,0) as isnum

from

p_cond as a

left join

(select p_cond_id,count(*) as counts from p_cond_han group by p_cond_id) as b

on a.id=b.p_cond_id

sqlserver用上边写法

mysql把isnull换成ifnull

oracle把isnull换成nvl