mysql - SELECT 语句 WHERE BETWEEN 计算字段 - 空结果

Question

我在使用 MySQL 中的 select 语句时遇到问题。

我有两个陈述只是略有不同，第一个似乎有效，但第二个无效。第二条语句返回 0 个结果。我错过了什么/做错了什么？

设置变量

SET @maxOK = 1.2;
SET @minOK = .8;

1# 不介于

SELECT *, fee - (receipts * -1) AS difference
FROM div.Data1
WHERE (receipts * -1) NOT BETWEEN (fee * @minOK) AND (fee * @maxOkay);

2# 之间

SELECT *, fee - (receipts * -1) AS difference,
          receipts * -1 as rec,
          fee * @minOk as min, fee * @maxOk as max
FROM div.Data1
WHERE (receipts * -1) BETWEEN (fee * @minOK) AND (fee * @maxOkay);

一些数据应该显示成两个但没有显示

SELECT *, fee - (receipts * -1) AS difference,
          receipts * -1 as rec,
          fee * @minOk as min, fee * @maxOk as max
FROM div.Data1

Answer 1

您的陈述有误。您已经声明了 @maxOk，但在您的 BETWEEN 子句中使用了 @maxOkay。

因为 @maxOkay 没有在任何地方声明，它被初始化为 NULL 所以你的声明基本上可以归结为

SET @maxOK = 1.2;
SET @minOK = .8;

SELECT *
       , fee - (receipts * -1) AS difference
       , receipts * -1 as rec
       , fee * @minOk as min
       , fee * @maxOk as max
FROM Data1
WHERE (receipts * -1) BETWEEN (fee * @minOK) AND NULL

声明应该是

SET @maxOK = 1.2;
SET @minOK = .8;

SELECT *
       , fee - (receipts * -1) AS difference
       , receipts * -1 as rec
       , fee * @minOk as min
       , fee * @maxOk as max
FROM Data1
WHERE (receipts * -1) BETWEEN (fee * @minOK) AND (fee * @maxOK);