How to find min() value in MYSQL

I have in my DB a column of varchar type.

Table name: Transcations

Column name :authprocess

I want to find min() value on the varchar column.

authprocess  

A1D1

A1D3

A1D4

A1D1

A1B1

A1D5  
......

i am using the command

select min(authpr开发者_Go百科ocess) from Trnascation

then it give the "0000" value

Please tell me the command in Mysql.

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MIN() makes no real sense for a character string, your best bet is to do a string sort by ascending values and select the top one perhaps??

SELECT TOP 1 FROM table ORDER ASC;

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MIN() takes the first entry after sorting. For text columns, the sorting order is ascii order, so for alpha-numeric data it's 0..9a..zA..Z

You must have an entry with the value 0000, which will of course be the minimum.

It sounds like you need to restrict your search to "valid" entries. Assuming entries are valid if they have form letter-digit-letter-digit, try this:

select min(authprocess)
from Transcations
where authprocess regexp '[A-Z]\d[A-Z]\d'

You can adjust the regex to suit whatever your needs are - eg perhaps it's A-digit-D-digit, which would match the regex 'A\dD\d'