mysql md5（md5（'pass'）+ salt）不等于php md5（md5（'pass'）。salt）

MySql query:

select md5(md5('pass') + '123') from foo

gives c8ffe9a587b126f152ed3d89a146b445
while php md5(md5('pass').'123')
gives ae2553fb5786e36233d25c879faf3863

What is wrong?

select md5(CONCAT(md5('pass'), '123'))

+ is probably adding it.

That's not how you concatenate strings in MySQL. See for yourself: SELECT 'pass' + '123';

Instead try SELECT md5(concat(md5('pass'), '123')) from foo