一个值对应多个字段查询 or and
$sql=array(
'$or'=>array(
["title"=>['$regex' => $keyword]],
["title_tw"=>['$regex' => $keyword]],
),
"status"=>1,"type" =>['$in' => $types]
);
$or 必须为一个数组才可以
查询某个字段值不为空 查询某个字段值不为空
$sql=array(
"img" =>['$exists' => 1]
);