MySQL的 - 從虛擬列中獲取最高價值

Question

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：

1 

1 

1 

2 

2 

3 

3 

我想從new_number_option列的最高值。這裏3是最高值。所以，我想獲得包含最高價值的記錄。我在上面的查詢中嘗試了HAVING MAX（new_number_option）。但是，它不會起作用。

Answer 1

嘗試CAST因爲你的列類型是string

CAST(new_number_option as SIGNED) 

使用

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

Answer 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' 

這將工作

希望這有助於..