DBD::mysql::st execute失败:未知列

这里的问题是不理解的 字符串插值

你用的是双引号( " )将查询字符串分配给 $q ,但它包含一个arobas( @ ),这是插值的。

q美元 最终包含:

SELECT SUBSTRING(AR_email, LOCATE(', AR_email) + 1) AS domain
FROM carrier
WHERE AR_email IS NOT NULL
AND SUBSTRING(AR_email, LOCATE(', AR_email) + 1) =?

如果你把这个放在下面 use warnings ,您将收到以下消息:

Possible unintended interpolation of @' in string

my $q = q/SELECT SUBSTRING(AR_email, LOCATE('@', AR_email) + 1) AS domain  
         FROM carrier 
         WHERE AR_email IS NOT NULL 
         AND SUBSTRING(AR_email, LOCATE('@', AR_email) + 1) =?/; 

故事的寓意:

• 仅当您 做

• 总是 use strict; use warnings;