一列的 MySQL SUM，只取相同字段之一

Question

Take a total for one column, but only need to take one row for the duplicate

+---------------------------+--------+
| orderId     | amount               |
+---------------------------+--------+
| 2           |   2000               |
| 2           |   2000               |
| 5           |   2000               |
| 7           |   5000               |
+---------------------------+--------+

I hope to get a total of 9000 instead of 11000

I want the total value of different orderIds, not the total value of the same orderId, so I can't use group by.

Answer 1

Using MAX(amount) with GROUP BY will avoid the duplicate entries, then SUM() will return the expected result:

SELECT SUM(Amount) AS SumAmount 
FROM (
    SELECT orderId, MAX(amount) AS Amount
    FROM TableName
    GROUP BY orderId
) A

Please find the working demo on db<>fiddle

Answer 2

尝试这个：

select orderId, sum(amount) from tmp_tbl group by orderId;

Answer 3

If you are using MySQL 8+, then ROW_NUMBER provides one option here:

WITH cte AS (
    SELECT *, ROW_NUMBER() OVER (PARTITION BY orderId ORDER BY orderId) rn
    FROM yourTable
)

SELECT SUM(amount)
FROM cte
WHERE rn = 1;

The ordering used by ROW_NUMBER above is arbitrary, but this is a good general approach in case you want to use different logic later on regarding which of the duplicate records to include in the sum.

Answer 4

SELECT SUM(Amount) AS SumAmount FROM TablName where orderid = ( SELECT Distinct(orderId) FROM TableName )

I have corrected the query

Answer 5

I think the best query would be

SELECT SUM(Amount) AS SumAmount,  COUNT(orderId)
FROM yourTable
GROUP BY orderId
HAVING COUNT(orderId) > 1;