求助如何用thinkphp的查询语言做到下面这样的查询。。
table a (分类表)
id name
1 l
2 ll
3 lll
table b (内容表)
id cid xname
1 2 x
2 1 xx
3 2 xxx
4 1 xxxxx
5 1 xxxxxxx
select a.id,a.name,(select count(id) as counts from b where b.cid=a.id) from a
//查询分类下的项目数，没有的显示0，及分类id，名称
return ：
id name counts
1 l 3
2 ll 2
3 lll 0
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$Model = M('A');
$Model->field('a.id,a.name,count(a.id)')->join('LEFT JOIN B ON A.id = B.cid')->group(a.id)->select();
使用虚拟模型 进行多表查询
//$table['表'] = 别名
$table['a'] = a;//a表
$thble['b'] = b;//b表
$this->Table($table)->Where('b.cid = a.id')->getfield('a.id,a.name,count(b.id) as counts');
重点在：GROUP BY a.id