CREATE TABLE t1 (i int);

INSERT INTO t1 VALUES (1),(2),(3);

WITH c1 AS (SELECT * FROM c2),

     c2 AS (SELECT * FROM t1)

SELECT * FROM c1;

WITH c1 AS (WITH c3 AS (SELECT * FROM c2) SELECT * FROM c3),

     c2 AS (SELECT * FROM t1)

SELECT * FROM c1;

MariaDB [test]> CREATE TABLE t1 (i int);

Query OK, 0 rows affected (0.16 sec)

MariaDB [test]> INSERT INTO t1 VALUES (1),(2),(3);

Query OK, 3 rows affected (0.06 sec)

Records: 3  Duplicates: 0  Warnings: 0

MariaDB [test]> WITH c1 AS (SELECT * FROM c2),

    ->      c2 AS (SELECT * FROM t1)

    -> SELECT * FROM c1;

ERROR 1146 (42S02): Table 'test.c2' doesn't exist

MariaDB [test]> WITH c1 AS (WITH c3 AS (SELECT * FROM c2) SELECT * FROM c3),

    ->      c2 AS (SELECT * FROM t1)

    -> SELECT * FROM c1;

+------+

| i    |

+------+

|    1 |

|    2 |

|    3 |

+------+

3 rows in set (0.00 sec)

+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------+

| id   | select_type | table | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra |

+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------+

|    1 | SIMPLE      | t1    | ALL  | NULL          | NULL | NULL    | NULL |    3 |   100.00 |       |

+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------+

1 row in set, 1 warning (0.00 sec)

MariaDB [test]> show warnings;

+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

| Level | Code | Message                                                                                                                                                                                                                      |

+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

| Note  | 1003 | with c1 as (with c3 as (select `test`.`t1`.`i` AS `i` from `test`.`t1`)select `test`.`t1`.`i` AS `i` from `test`.`t1`), c2 as (select `test`.`t1`.`i` AS `i` from `test`.`t1`)select `test`.`t1`.`i` AS `i` from `test`.`t1` |

+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+