mysql - 从虚拟列中获取最高值答案

【问题标题】：mysql - get highest value from virtual columnmysql - 从虚拟列中获取最高值
【发布时间】：2015-11-03 04:58:05
【问题描述】：

SELECT *, REPLACE(number_option, 'Issue ', '') AS new_number_option FROM
jgl_article WHERE status = 1 AND topic = 'Current Issues' ORDER BY id ASC

new_number_option 列返回：

我想从 new_number_option 列中获取最高值。这里 3 是最高值。所以，我想获取包含最高价值的记录。我在上面的查询中尝试了 HAVING MAX(new_number_option) 。但是，它不起作用。

【问题讨论】：

标签： mysql sql select where

【解决方案1】：

试试CAST，因为您的列类型是string

CAST(new_number_option as SIGNED)

使用

MAX( CAST(REPLACE(number_option, 'Issue ', '') AS UNSIGNED) )

【讨论】：

它只返回第一行。它不返回包含最高值的行
SELECT *, MAX( CAST(REPLACE(number_option, 'Issue ', '') AS UNSIGNED) ) AS new_number_option FROM jgl_article WHERE status = 1 AND topic = 'Current Issues'
试试这个查询@Beginner
也试过了。不会工作。我想获取所有包含 new_number_option = MAX(new_number_option) 的记录
SELECT * from jgl_article WHERE REPLACE(number_option, 'Issue ', '') in (SELECT MAX(CAST(REPLACE(number_option, 'Issue ', '') AS UNSIGNED)) from jgl_article WHERE status = 1 AND 主题 = '当前问题')

【解决方案2】：

SELECT JA.*
  FROM
jgl_article JA INNER JOIN
     (SELECT MAX( CAST(REPLACE(number_option, 'Issue ', '') AS UNSIGNED) ) AS MAX_number_option FROM
      jgl_article) T
              ON CAST(TRIM(JA.number_option) as UNSIGNED) = T.MAX_number_option
WHERE JA.status = 1 AND JA.topic = 'Current Issues'

这会起作用

希望这会有所帮助..

【讨论】：

再试一次，我错过了昏迷
返回空结果集
在 'as UNSIGNED 附近使用) = T.MAX_number_option WHERE JA.status = 1 AND JA.topic = 'Current ' 在第 6 行
是的..别名错误..我已修复
“订单子句”中的未知列“JA.new_number_option”