如何在没有公共列的情况下加入2个表？

Question

我有2张桌子

User Code         SubMenuID

usercol           menucol 
-----------       -------------
AB                Sub-01 
Alam              Sub-02 
CSRL

我想像这样展示他们

usercol           menucol
----------        ------------
AB                Sub-01 
AB                Sub-02 
Alam              Sub-01
Alam              Sub-02 
CSRL              Sub-01 
CSRL              Sub-02

我怎么能用sql查询得到这个？这会非常有帮助:)

Answer 1

Since the tables are not related by a foreign key relationship, you can not join them - what you want as a result, is the Cartesian product from the two tables. This is achieved by selecting from both tables without any additional join condition (this is also called a cross join):

mysql> SELECT * FROM userCode, SubMenuId;

This query combines all rows from the first table with all rows from the second table.

+---------+---------+
| usercol | menucol |
+---------+---------+
| AB      | Sub-01  |
| AB      | Sub-02  |
| Alam    | Sub-01  |
| Alam    | Sub-02  |
| CSRL    | Sub-01  |
| CSRL    | Sub-02  |
+---------+---------+