Question

此语句将生成一个4列表：

SELECT shipped.badguy AS badguy, shipped.sdate AS LineDate,
        'Delivery' AS Legend, -price*quantity AS amount
    FROM product JOIN shipped ON (product.id = shipped.product)
UNION
  SELECT receipt.badguy, receipt.rdate,notes, amount
  FROM receipt

如何获得上述产生的第4列的总和？

Answer 1

SUM(-price*quantity)

啊？

Answer 2

尝试

sum(price*quantity)

或将两个查询合并为

SELECT badguy,rdate,notes,SUM(AMOUNT) FROM(
        SELECT shipped.badguy AS badguy, shipped.sdate AS LineDate, 
        'Delivery' AS Legend, -price*quantity AS amount 
    FROM product JOIN shipped ON (product.id = shipped.product) 
UNION 
  SELECT receipt.badguy, receipt.rdate,notes, amount 
  FROM) A

Answer 3

我喜欢使用子查询。

SELECT SUM(results.amount)
FROM
(
SELECT -price*quantity AS amount 
    FROM product JOIN shipped ON (product.id = shipped.product) 
UNION 
  SELECT amount 
  FROM  
...
) results

Answer 4

将查询包装在另一个查询中，外部查询只获取所需的总和。这使您的查询成为子查询。

SELECT SUM(amount) FROM (
   SELECT shipped.badguy AS badguy, shipped.sdate AS LineDate,
           'Delivery' AS Legend, -price*quantity AS amount
       FROM product JOIN shipped ON (product.id = shipped.product)
   UNION
     SELECT receipt.badguy, receipt.rdate,notes, amount
     FROM <...>
)

我如何得到第4列的总和

4 个答案: