Question

我的SUM条件为负整数会导致计算错误。

如果CN（贷方）为true，则必须将该行的总计设置为负，然后将总计加在一起。

+----+-------+------------+-------+
| id | CN    | date       | total |
+----+-------+------------+-------+
| 1  | false | 2019-01-01 | 30    |
+----+-------+------------+-------+
| 2  | true  | 2019-01-01 | 15    |
+----+-------+------------+-------+

SELECT 
  MONTH(invoices.date) as month,
  IF(invoices.CN = true,
    CAST(SUM(DISTINCT COALESCE(invoices.total * -1, 0)) AS SIGNED),
    CAST(SUM(DISTINCT COALESCE(invoices.total, 0)) AS SIGNED)) AS total,
  from invoices
  GROUP BY month

结果

+-------+------+
| month | total|
+-------+------+
| 1     | -30  |
+-------+------+

我期望：30 +（-15）= 15

+-------+------+
| month | total|
+-------+------+
| 1     |  15  |
+-------+------+

Answer 1

这符合您的想法：

SELECT
    MONTH(date) AS month,
    SUM(CASE WHEN CN = 'true' THEN -1.0 * total ELSE total END) AS total
FROM invoices
GROUP BY
    MONTH(date);

我说这很接近，因为目前尚不清楚CN如何或为什么最终出现在汇总结果中。对我来说，只报告月份和总数是很有意义的。

Answer 2

DROP TABLE IF EXISTS my_table;

CREATE TABLE my_table (cn TINYINT, total INT);

INSERT INTO my_table VALUES (false,30),(true,15);    

SELECT SUM((0.5-cn)*2*total)x FROM my_table;
+------+
| x    |
+------+
| 15.0 |
+------+
1 row in set (0.00 sec)

总和负整数给出错误的结果

2 个答案: