我有两张桌子:
table_a: table_b
+----+------+ +----+---------+------+
| id | name | | id | relation| name |
+----+------+ ++++++---------+------+
| 1 | bob | | 1 | friend | chris|
| 2 | jim | | 1 | friend | jon |
| 3 | tom | | 1 | brother | matt |
+----+------+ | 2 | friend | sam |
| 2 | parent | ron |
+----+---------+------+
我想输入一个查询输出类似的东西
+----+------+------------+---------+--------+
| id | name |friend | brother | parent …