mysql - 将两个 MYSQL SELECT 语句组合/合并为一个

Question

我正在使用单个 SELECT 语句寻求帮助。使用两个语句的示例:

1st: get 40 days from now out to 365 days from now

2nd: get NOW out to 40 days

等于所有 365 天从现在开始偏移 40 天

选择语句1:

SELECT id FROM sales
 WHERE (saledate BETWEEN DATE_ADD(NOW(), INTERVAL 40 DAY) AND DATE_ADD(NOW(), INTERVAL 365 DAY))
 ORDER BY saledate;

选择语句2:

SELECT id FROM sales
 WHERE (saledate BETWEEN NOW() AND DATE_ADD(NOW(), INTERVAL 40 DAY))
 ORDER BY saledate;

Answer 1

为什么不直接使用或呢？

SELECT id
FROM sales
WHERE (saledate BETWEEN DATE_ADD(NOW(), INTERVAL 40 DAY) AND DATE_ADD(NOW(), INTERVAL 365 DAY)) OR
       (saledate BETWEEN NOW() AND DATE_ADD(NOW(), INTERVAL 40 DAY))
ORDER BY saledate;

当然，这可以进一步简化:

SELECT id
FROM sales
WHERE saledate BETWEEN (NOW() AND DATE_ADD(NOW(), INTERVAL 365 DAY)
ORDER BY saledate;

虽然这看起来很明显，但我可能遗漏了什么。

编辑:

如果这是一个排序问题，那么 union all 不是要走的路。联合不保证结果的顺序。相反，只需执行以下操作:

SELECT id
FROM sales
WHERE saledate BETWEEN (NOW() AND DATE_ADD(NOW(), INTERVAL 365 DAY)
ORDER BY (saledate >= DATE_ADD(NOW(), INTERVAL 40 DAY) ) DESC,
         saledate;