简单的方法来创建varchar格式的4-6个字符id

Question

I need to have a really simple way to make a shortened id that's always unique. For example, something is created and given a normal auto increment id. I need to have an alternative id if you will that's 4-6 characters.

something like a1b2 or abcd. they always need to be unique though. Please help if you can.

Answer 1

substr(str_shuffle(str_repeat('ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789',5)),0,5);

The only way to test if its unique is to check against your database. The possible space with only 4-6 char long strings is relatively small, collisions are quite likely.