MySQL 列 AS 与 BETWEEN 导致错误

Question

我有一个问题，我需要在 MySQL 查询中作为一列并在该列上执行 BETWEEN 。我能想到的说明问题的最简单版本是这样的：

SELECT ID AS post_id FROM wp_posts WHERE (post_id BETWEEN 10 AND 20)

这会引发以下错误：

#1054 - Unknown column 'post_id' in 'where clause'

有没有办法使新创建的 post_id 列对 BETWEEN 运算符可见？

更新：

这是我的实际查询。正如您所看到的，它稍微复杂一些：

SELECT wp_postmeta.post_id,
MAX(CASE WHEN wp_postmeta.meta_key='store_lng' THEN wp_postmeta.meta_value END ) AS lng,
MAX(CASE WHEN wp_postmeta.meta_key='store_lat' THEN wp_postmeta.meta_value END ) AS lat
FROM wp_postmeta
LEFT JOIN wp_posts ON (wp_posts.ID=wp_postmeta.post_id) 
WHERE
(lng BETWEEN 150.29793837662 AND 152.1161201948)
AND 
(lat BETWEEN -34.775666623377 AND -32.957484805195) 
AND
wp_posts.post_status='publish'
AND
wp_posts.post_type='store'
GROUP BY wp_postmeta.post_id

Answer 1

来自 MySQL 文档：

不允许引用
WHERE 子句中的列别名，
因为列值可能还没有
当 WHERE 子句为
已执行。

您必须在 WHERE 子句中使用 ID 而不是 post_id，或者使用 HAVING 子句。

例如：

SELECT ID AS post_id FROM wp_posts WHERE ID BETWEEN 10 AND 20

更新：根据您最近的更新，您可以按照已经建议的方式使用子查询，或者按照我之前的建议，您可以使用 HAVING 子句。

例如：

SELECT    wp_postmeta.post_id,
          MAX(CASE WHEN wp_postmeta.meta_key = 'store_lng' THEN wp_postmeta.meta_value END) AS lng,
          MAX(CASE WHEN wp_postmeta.meta_key = 'store_lat' THEN wp_postmeta.meta_value END) AS lat
FROM      wp_postmeta
LEFT JOIN wp_posts
ON        wp_posts.ID = wp_postmeta.post_id
WHERE     wp_posts.post_status = 'publish' AND
          wp_posts.post_type = 'store'
GROUP BY  wp_postmeta.post_id
HAVING    lng BETWEEN 150.29793837662 AND 152.1161201948 AND 
          lat BETWEEN -34.775666623377 AND -32.957484805195

Answer 2

标准 SQL 不允许在 WHERE 子句中引用列别名。

施加此限制是因为当计算 WHERE 子句时，列值可能尚未确定。
(http://dev.mysql.com/doc/ refman/5.0/en/problems-with-alias.html）

Answer 3

是的，你可以！

SELECT post_id
from (select id AS post_id FROM wp_posts) x
WHERE post_id BETWEEN 10 AND 20

编辑以包括对问题的更改。试试这个（还没有在mysql中运行过，但如果不正确的话应该接近）：

SELECT *
FROM (SELECT
  wp_postmeta.post_id,
  MAX(CASE WHEN wp_postmeta.meta_key='store_lng' THEN wp_postmeta.meta_value END ) AS lng,
  MAX(CASE WHEN wp_postmeta.meta_key='store_lat' THEN wp_postmeta.meta_value END ) AS lat 
FROM wp_postmeta
GROUP BY wp_postmeta.post_id
) x
LEFT JOIN wp_posts ON wp_posts.ID = x.post_id
WHERE lng BETWEEN 150.29793837662 AND 152.1161201948
AND lat BETWEEN -34.775666623377 AND -32.957484805195
AND wp_posts.post_status='publish'
AND wp_posts.post_type='store'