SQL-没有主键的串联

Question

我有两个不共享主键的表（A和B）。我需要某种连接，其中如果date_B ，我必须为表A中的每一行添加表B中的行。

*日期格式：yyyy-mm-dd

表A

+-------+-----+-----------+
| id_A  | op_A|   date_A  |
+-------+-----+-----------+
| 1     |  0  | 2018-10-01|
| 2     |  0  | 2018-12-31| 
+-------+-----+-----------+

表B

+-----+--------+-------------+
| id_b| other  |  date_B     |
+-----+--------+-------------+
| a   |  8     | 2018-09-01  |
| b   |  90    | 2018-12-01  | 
+-----+--------+-------------+

正确的结果：

+-----+-----+-----------+-----+--------+-------------+
| id_A| op_A|   date_A  | id_B| other  |  date_B     |
+-----+-----+-----------+-----+--------+-------------+
| 1   |  0  | 2018-10-01| a   |  8     | 2018-09-01  |
| 2   |  0  | 2018-12-31| a   |  8     | 2018-09-01  |
| 2   |  0  | 2018-12-31| b   |  90    | 2018-12-01  |  
+-----+-----+-----------+-----+--------+-------------+

Answer 1

此查询应为您提供所需的结果：

SELECT *
FROM TableA a
JOIN TableB b ON b.date_B < a.date_A

输出：

id_A    op_A    date_A      id_b    other   date_B
1       0       2018-10-01  a       8       2018-09-01
2       0       2018-12-31  a       8       2018-09-01
2       0       2018-12-31  b       90      2018-12-01

Demo on SQLFiddle