在 MySQL 中對 UNION 結果求和的簡單方法

Question

我有三個表（t1、t2、t3）的聯合。
每次重新運行完全相同數量的記錄，第一列是id ，第二列是amount ：

1  10
2  20
3  20

1  30
2  30
3  10

1  20
2  40
3  50

SQL有沒有簡單的方法總結一下，即只得到：

1   60
2   80
3   80

Answer 1

select id, sum(amount) from (
    select id,amount from table_1 union all
    select id,amount from table_2 union all
    select id,amount from table_3
) x group by id

Answer 2

SELECT id, SUM(amount) FROM
(
    SELECT id, SUM(amount) AS `amount` FROM t1 GROUP BY id
  UNION ALL
    SELECT id, SUM(amount) AS `amount` FROM t2 GROUP BY id
) `x`
GROUP BY `id`

我將每個表分組並合並，因為我認為它可能更快，但您應該嘗試兩種解決方案。

Answer 3

子查詢：

SELECT id, SUM(amount)
FROM ( SELECT * FROM t1
       UNION ALL SELECT * FROM t2
       UNION ALL SELECT * FROM t3
     )
GROUP BY id

Answer 4

不確定 MySQL 是否使用公共表表達式，但我會在 postgres 中這樣做：

WITH total AS(
              SELECT id,amount AS amount FROM table_1 UNION ALL
              SELECT id,amount AS amount FROM table_2 UNION ALL
              SELECT id,amount AS amount FROM table_3
             )
SELECT id, sum(amount)
  FROM total

我認為這也應該可以解決問題。

Answer 5

由於之前的答案不是很清楚，請記住提供別名（在 MySQL/MariaDb 上），否則會出現錯誤：

每個派生表都必須有自己的別名

select id, sum(amount) from (
    select id,amount from table_1 union all
    select id,amount from table_2 union all
    select id,amount from table_3
) AS 'aliasWhichIsNeeded'
 group by id

Answer 6

是的！！！ 沒關系！ 謝謝！！！！ 我的代碼整理：

SELECT SUM(total) 
FROM ( 
        (SELECT 1 as id, SUM(e.valor) AS total  FROM entrada AS e)
    UNION 
        (SELECT 1 as id, SUM(d.valor) AS total FROM despesa AS d)
    UNION 
        (SELECT 1 as id, SUM(r.valor) AS total FROM recibo AS r WHERE r.status = 'Pago')
)  x group by id

Answer 7

SELECT      BANKEMPNAME,  workStation, SUM (CALCULATEDAMOUNT) FROM(
SELECT      BANKEMPNAME, workStation, SUM(CALCULATEDAMOUNT) AS CALCULATEDAMOUNT,SALARYMONTH
FROM        dbo.vw_salaryStatement
WHERE       (ITEMCODE  LIKE 'A%') 
GROUP BY    BANKEMPNAME,workStation, SALARYMONTH
union all
SELECT      BANKEMPNAME, workStation,  SUM(CALCULATEDAMOUNT) AS CALCULATEDAMOUNT,SALARYMONTH
FROM        dbo.vw_salaryStatement
WHERE       (ITEMCODE  NOT LIKE 'A%')
GROUP BY    BANKEMPNAME, workStation, SALARYMONTH) as t1
WHERE       SALARYMONTH BETWEEN '20220101' AND '20220131'
group by    BANKEMPNAME,  workStation
order by    BANKEMPNAME asc

在 MSSQL 中，您可以用這種方式編寫查詢，但是對兩個查詢執行聯合所有列應該是相同的..

我必須從我的項目中給出這個例子，這樣你才能理解這個過程。