mysql - Date in mysql select

Question

I have a table A:

A.date | A.price
2013-10-01 | 5000
2013-10-02 | 5000
2013-10-03 | 5000
2013-10-04 | 5000
2013-10-05 | 5000

and table B:

B.date | B.price
2013-10-01 | 3500
2013-10-03 | 1600

In output I would like to receive the following information:

2013-10-01 | 3500
2013-10-02 | 5000
2013-10-03 | 1600
2013-10-04 | 5000
2013-10-05 | 5000

How to do it, help!

Answer 1

您可以使用 LEFT JOIN，并且可以尝试将表 A 与表 B 连接：

SELECT
  A.date,
  COALESCE(B.price, A.price)
FROM
  A LEFT JOIN B ON A.date=B.date

如果连接不成功，B.price 将为 NULL，否则它将有一个值。使用 COALESCE() 您可以获得第一个非空值。

请在此处查看小提琴。