合并两个相似的选择删除两个文件复制

Question

我有2个选择返回此字段。 选择1：

+-----------+---------+-------+
| serviceID | modelID | price |
+-----------+---------+-------+
|  1        | 100     |   0   |
+-----------+---------+-------+
|  2        | 100     |   0   |
+-----------+---------+-------+
|  1        | 200     |   0   |
+-----------+---------+-------+
|  2        | 200     |   0   |
+-----------+---------+-------+

SELECT 2

+-----------+---------+-------+
| serviceID | modelID | price |
+-----------+---------+-------+
|  1        | 100     |   499 |
+-----------+---------+-------+

我需要这样的结果：

+-----------+---------+-------+
| serviceID | modelID | price |
+-----------+---------+-------+
|  1        | 100     |   499 |
+-----------+---------+-------+
|  2        | 100     |   0   |
+-----------+---------+-------+
|  1        | 200     |   0   |
+-----------+---------+-------+
|  2        | 200     |   0   |
+-----------+---------+-------+

即。全部来自选择1，但如果选择2有fld替换为select1

Answer 1

SELECT A.serviceID, A.modelID, IF(B.price IS NULL, A.price, B.price) AS price
FROM table1 A LEFT JOIN table2 B ON
A.serviceID = B.serviceID AND A.modelID= B.modelID

Answer 2

select * from (
( select 2 here ) union ( select 1 here ) ) as r group by serviceID, modelID

这对我有用。可能它会帮助某人。