How to auto increment by 2 for a particular table in mysql

Question

I have 2 tables order_retailer and order_customer

they both have auto incremented primary key order_id

To keep an order id unique in the whole system I want

Answer 1

You can offset one table's auto increment field from the other, i.e. one table starts ids from 1 while the other starts from 1000000 (or some other value chosen depending on your usage pattern).

CREATE TABLE table1 (id BIGINT UNSIGNED AUTO_INCREMENT);
CREATE TABLE table2 (id BIGINT UNSIGNED AUTO_INCREMENT) AUTO_INCREMENT = 1000000;

You can also choose your autoincrement column type according to your needs. BIGINT UNSIGNED's range is 0..18446744073709551615, which should cover most cases.

OR

try

SET @@auto_increment_increment=2;
SET @@auto_increment_offset=2;