[英]Mysql string/number order
您好,我有一個索引字符串字段,可以包含字符串或數字。 我想獲取此索引的最大值和最小值,但我希望僅DIGITS索引的順序為整數,否則為字符串。 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
我嘗試了這個:
MAX(IF(CAST(idxfield as UNSIGNED)=0,CAST(idxfield as UNSIGNED),idxfield)) as maxField
但是不起作用。
您可以使用REGEXP
來測試該字段是否為數字。
例如:
select '1' REGEXP '^[0-9]+$'; // returns 1
select 'A' REGEXP '^[0-9]+$'; // returns 0
嘗試這個 ::
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
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