SQL添加具有相同ID的不同行的值

Question

Query:

SELECT code, duration 
FROM table1

results in

code	duration
234	3
345	2
345	3
456	4
567	5
567	6
567	1

I would like to add the durations of the same code and display results as here

code	duration
234	3
345	5
456	4
567	12

but I don't know where to start with this query?

Answer 1

你使用聚合函数SUM

SELECT code, SUM(duration) FROM table1 GROUP BY code

Answer 2

You can use GROUP BY together with SUM . When using GROUP BY , aggregate functions (such as SUM ) will return the output of the function as if every value in the specified column for the entire group was passed to it. In this case you can tell it to run on duration .

SELECT code, SUM(duration) as TotalDuration FROM table1 GROUP BY code