Magento – Change Order Number and Invoice Number

It is possible to create a completely new EAV increment model. This is where the magic happens when getting the next ids :)

Firstly you can see what the current model is by looking at the table eav_entity_type under the column increment_model. For example to order has the following set.

eav/entity_increment_numeric

You can create your new model and set it for orders via an install script.

class My_CustomEav_Model_Entity_Increment_New extends Mage_Eav_Model_Entity_Increment_Abstract
{
    public function getNextId()
    {
        // Some magic here to get the unique  vaue you want and return it
    }
}

The table eav_entity_store holds a few more pieces of important information. Here you can store increment_prefix varchar(20) which is the prefix that is normally added to the increment, I think the default it 1, and increment_last_id varchar(50) this stores the last id used for the entity type on a given store, note that without changing the table definition you will be limited to varchar(50), though that should be enough....maybe.

NOTE I have not tested this myself as I have never needed to but it should all work nicely if the ids are unique.

If I want to continue using Magento's default increment type and just want to change the next increment number, this is what I use.

Be sure to only use increment numbers that are larger then ones already used!

SET @next_increment='310000000';

SELECT @entity_types:=GROUP_CONCAT(`entity_type_id`) FROM `eav_entity_type`
    WHERE `entity_type_code` IN ('order', 'invoice', 'shipment');

SELECT @new_last_increment:=GREATEST((@next_increment -1), 
    (SELECT MAX(`increment_last_id`) FROM `eav_entity_store`
     WHERE FIND_IN_SET(`entity_type_id`, @entity_types)));

UPDATE `eav_entity_store` SET `increment_last_id`=@new_last_increment
    WHERE FIND_IN_SET(`entity_type_id`, @entity_types);

This SQL should take care of not accidentially setting an increment ID that was used already.
If a larger increment then next_increment already was used, it simply sets the last increment number for all three entity types to be the same.