vQmod conflict

2 different objects cannot occupy the exact same space at the same time. That is why it is important that when using search/replace that you match the least amount as possible while still being unique. This will better your chances of something like this:

Base string:

SELECT * FROM product WHERE product_id = '1' AND status = '1';

If mod 1 wants to change it to:

SELECT * FROM product WHERE product_id = '1' AND model = 'xyz' AND status = '1';

and mod 2 wants to change it to:

SELECT * FROM product WHERE product_id = '1' AND sku = 'xyz' AND status = '1';

Then it is important that both vQmod authors DO NOT try to do:

<search position="replace">
SELECT * FROM product WHERE product_id = '1' AND status = '1';
</search>
<add>
SELECT * FROM product WHERE product_id = '1' AND model = 'xyz' AND status = '1';
</add>

But instead use a smaller chunk like:

<search position="replace">
SELECT * FROM product WHERE product_id = '1'
</search>
<add>
SELECT * FROM product WHERE product_id = '1' AND model = 'xyz'
</add>

Then the other mod could use the same search and not break from the first line:

 

<search position="replace">
SELECT * FROM product WHERE product_id = '1'
</search>
<add>
SELECT * FROM product WHERE product_id = '1' AND sku= 'xyz'
</add>

Resulting in the proper combined result:

SELECT * FROM product WHERE product_id = '1' AND sku = 'xyz' AND model = 'xyz' AND status = '1';

Source: http://forum.opencart.com/viewtopic.php?f=131&t=46247