laravel orm 关联条件查询代码

public function a()
{
  return $this- belongsTo('App\Models\a', 'aid');
}
$model = $this- whereHas('a', function ($query) use ($search) {
  $query- where('username', 'like', '%' . $search['username'] . '%');
})- with(['a:id,username'])- get();

select a.id,a.username,b.* from b left join a on a.id = b.aid where a.username like "%username%";