php - 使用 bool 值php计算mysql中的列总和

Question

我有一个名为 expenses 的表，它包括以下几列:

ID, amount_1, amount_2, amount_1_paid, amount_2_paid, total

amount_x_paid 是一个 TINYINT，所以它用于复选框。

我想做的是根据amount_x_paid值(1,0)计算总数

让我们说:

amount_1 = 100
amount_2 = 200
amount_1_paid = 1
amount_2_paid = 0

这应该计算

 total = 100

如何在 php 中实现这一点？

php 文件将是一个计划任务作业，每天运行一次以计算总数。

这可以解决问题:

SELECT
 FORMAT(
   SUM(
     CASE
       WHEN amount_1_paid = 0 THEN (total + amount_1)
 ELSE (total - amount_1)
       END
    ),
    0
  )
AS total
  FROM
    expenses  
    WHERE ID = '1';

我怎样才能把它放在一个循环中并更新所有记录？

Answer 1

要根据 amount_x_paid 列选择 amount_ 字段，您可以使用 CASE 表达式。像这样:

SELECT
  CASE 
    WHEN amount_1_paid = 1 THEN amount_1 
    WHEN amount_2_paid = 1 THEN amount_2  
    ELSE 0
  END AS Amount,
  ...
FROM tablename;

如果您要查找这些金额的总和，请在子查询中使用它:

SELECT 
  SUM(Amount) AS Total,
  ...
FROM
(
    SELECT
      CASE 
        WHEN amount_1_paid = 1 THEN amount_1 
        WHEN amount_2_paid = 1 THEN amount_2  
        ELSE 0
      END AS Amount,
      ...
    FROM tablename
) AS sub;