mysql - Mysql 字符串/数字顺序

Question

您好，我有一个可以包含字符串或数字的索引字符串字段。我想得到这个索引的最大值和最小值，但我希望一个只有数字的索引是整数，否则是字符串。例如我想要：

   ( "1", "5", "10" )       MIN=1 MAX=10 // mind MAX=10 not 5 as string order!
   ( "A", "D", "Z" )        MIN=A MAX=Z

我试过这个：

MAX(IF(CAST(idxfield as UNSIGNED)=0,CAST(idxfield as UNSIGNED),idxfield)) as maxField

但不起作用。

Answer 1

尝试这个 ：：

Select 
idxfield REGEXP '[0-9] as field1,
CASE field1
 WHEN 1 THEN SELECT idxfield from table order by idxfield+0 desc
 WHEN 0 THEN SELECT idxfield from table order by idxfield desc
END as max_value,
CASE field1
 WHEN 1 THEN SELECT idxfield from table order by idxfield+0
 WHEN 0 THEN SELECT idxfield from table order by idxfield
END as min_value
from table

Answer 2

您可以REGEXP用来测试该字段是否为数字。

例如：

select '1'  REGEXP '^[0-9]+$'; // returns 1
select 'A'  REGEXP '^[0-9]+$'; // returns 0