php - 如何将此查询语句变成一条 查询语句

Question

$data = $w -> field('id,picurl') -> select();
foreach ($data as $key => $value) 
{
    $data[$key]['logoes'] = $wa -> field('id,logo') -> where('classid='.$value['id']) -> select();
}

Answer 1

$data = $w -> field('id,picurl') -> select();
//
$arr = $wa -> field('id,logo') -> wherein('classid',array_column($data,'id'))-> select();
$res = array_column($arr , null, 'id');
foreach ($data as $key => $value) 
{
    $data[$key]['logoes'] = $res[$value['id']];
}

Answer 2

select id,logo from db where classid in (select id from db)

Answer 3

SELECT a.id, a.picture, b.id as logo_id, b.logo FROM a,b WHERE a.id = b.classid

Answer 4

select a.id,a.picurl,b.id,b.logo from w as a left join wa as b on b.classid = a.id

两表联合查询解决