Mysql 将查询从不存在的位置转换为左联接

我使用的是laravel 5.2，转换此查询时遇到问题

 DB::select('SELECT m.*
            FROM member_table AS m
            JOIN treepaths AS t ON m.membershipid = t.descendant
            WHERE m.stage >=' . $usermatrixtype . '
            AND t.ancestor =' . "'" . $firstrightchildmembershipid . "'" . '
            AND NOT EXISTS (
            select user_id from matrix_users AS mr WHERE mr.user_id=m.membershipid AND matrix_id=' . $getusermatrix . '
            ) LIMIT ' . $results
);

这是我试过的

 DB::select('SELECT m.membershipid
            FROM member_table AS m
            JOIN treepaths AS t ON m.membershipid = t.descendant
            WHERE m.stage >=' . $usermatrixtype . '
            AND t.ancestor =' . "'" . $firstleftchildmembershipid . "'" .'
            LEFT OUTER JOIN matrix_users AS mu ON mu.user_id =m.membershipid WHERE
           matrix_id=' . $getusermatrix . ' AND
            mu.userid IS NULL
             LIMIT ' . $results);

它不返回任何内容

请尝试以下操作：

 DB::select('SELECT m.membershipid
            FROM member_table AS m
            JOIN treepaths AS t ON m.membershipid = t.descendant
            LEFT JOIN matrix_users AS mu ON mu.user_id =m.membershipid AND  matrix_id=' . $getusermatrix . '
            WHERE  mu.userid IS NULL AND m.stage >=' . $usermatrixtype . '
            AND t.ancestor =' . "'" . $firstleftchildmembershipid . "'" .'

             LIMIT ' . $results);

---

在您更改它之前，它是否工作正常？是的，但是非常慢。在第二次查询中，您试图匹配

mu.user\u id=m.membershipid

，然后在最后执行

，其中mu.userid为NULL

=这是问题吗？不，只是编辑了它，这不是问题。您找到了m.stage列