具有条件的字段的 MySQL SUM, IF(SUM(bill_1) IS NULL, '99', SUM(bill_1)) AS tot_bill_1

【问题标题】：MySQL SUM of field with conditon, IF(SUM(bill_1) IS NULL, '99', SUM(bill_1)) AS tot_bill_1具有条件的字段的 MySQL SUM, IF(SUM(bill_1) IS NULL, '99', SUM(bill_1)) AS tot_bill_1
【发布时间】：2015-04-15 21:50:51
【问题描述】：

我想要 SUM(tot_bill_1+tot_bill_2) 作为总计，但它不起作用

SELECT *, 
IF(SUM(bill_1) IS NULL, '99', SUM(bill_1)) AS tot_bill_1, 
IF(SUM(bill_2) IS NULL, '10', SUM(bill_2)) AS tot_bill_2, 
SUM(tot_bill_1+tot_bill_2) AS total
FROM billing

有什么想法吗？

【问题讨论】：

标签： mysql if-statement join sum conditional-statements

【解决方案1】：

您可以使用子查询来做到这一点：

SELECT sum_bill1,
       sum_bill2,
       (sum_bill1 + sum_bill2) AS total
FROM
  (SELECT COALESCE(sum(bill1), 99) AS sum_bill1,
          COALESCE(sum(bill2), 10) AS sum_bill2
   FROM billings) t

【讨论】：