sql count()一张表里的结果做为一列加到select语句里
有两张表，表A里有列：pot_id, gar_id, pot_value。表B里有列：gar_id, gar_name, gar_volume。其中表B里的主码是gar_id，gar_id也是表A的外码。
如果用两条语句表达，即：select COUNT(*) as gar_remain from A where pot_value = 0 group by gar_id; select gar_id, gar_name, gar_remain from B。怎么把两条语句写成一条？就作像: select gar_id, gar_name, COUNT(*) as gar_remain from A, B ...
[解决办法]
select b.gar_id, b.gar_name, b.gar_remain, gar_id from B
left join
(select gar_id,COUNT(*) as gar_remain from A where pot_value = 0 group by gar_id) c
on b.gar_id=c.gar_id
