PHP / MySQL使用varchar作为ID

Question

I have to create a database that contains some information about a few products and some SKU's, part of this is the product type and sub-type, having a total of 60-70 product types and 2-20 sub-types for each of them.

The part of SKU code that needs to be generated is in the form XXY, where XX is the product type and Y is the sub-type of it, for the type part it was easy to add a unique auto_increment field (since it will never go over 99) but for the sub-type part i need to use both numbers and letters in an order like 1-9-AZ.

What is the simplest way to achieve this ? I have some idea how to do it with javascript / json to check and retrieve the Y field but i got a feeling there must be an easier way with just using php/mysql for this.

Basically what i need is for php/mysql to generate a single-character "id subtype" from 1 to Z for each unique product type.

Answer 1

I'm afraid you'll have to use Javascript or PHP (or anything you are using server side) to generate this char. There's no builtin SQL function to do that. For your single-character id subtype you shouldn't use VARCHAR BUT CHAR(1) .

CHAR has a fixed length, therefore will take only 1 byte per character. VARCHAR takes the same as CHAR + 2 bytes to hold length information.

Example:

$characters = 'abcdefghijklmnopqrstuvwxyz0123456789'; 
$char = strtoupper($characters[rand(0, strlen($characters) - 1)]);