mysql - 如何在单个表MySQL中比较和求和不同的列

I have a table with some duplicate stock ids and release date.The table table data is like below.

|STOCK_ID       |QTY| release_date|
-----------------------------------
|4046228009711    |12 | 25.02.2015  |
|4046228009711    |3  | 21.12.2014  |
|4046228009711    |13 | 21.12.2014  |
|4046228009711    |5  | 21.12.2014  |
------------------------------------

Now i want to sum the quantity of same stock id and same released_date and segregate records based on the released_date.
So the  out put should be like this.This is the expected output

|STOCK_ID       |QTY| release_date|
-----------------------------------
|4046228009711    |12 | 25.02.2015  |
|4046228009711    |21 | 21.12.2014  |
-----------------------------------

为了实现这一点，我尝试了下面的查询。
为此，我在临时表中插入了相同的数据。

SELECT t1.STOCK_ID,t1.`released_date
(SELECT SUM(Qty) FROM
table1 t1
WHERE h1.STOCK_ID = t2.STOCK_ID AND t1.released_date = t2.released_date
) AS 'Bestand'
FROM table1 t1
JOIN table2 t2  ON t1.STOCK_ID = t2.STOCK_ID
GROUP BY t1.STOCK_ID

But i am getting the below output

|STOCK_ID       |QTY| release_date|
-----------------------------------
|4046228009711    |12 | 25.02.2015 |
-----------------------------------

在我犯错误的地方有人能帮我吗？任何帮助都将不胜感激。

最佳答案

可以这样做

select
STOCK_ID,
sum(QTY) as QTY,
release_date
from table_name
group by STOCK_ID,release_date