Database fields that you add are used in queries already calling some tables in the database.
Below is the list of tables used by grid, and you can use the aliases provided.
When PrestaShop version is >= 1.5:
When Prestashop version is >= 1.5:
message m (if Message column is used)
order_detail od (if In Stock column is used)
address ad (shipping address)
address adi (Invoice address)
storecom_delivery_info sdi (if SC Delivery Dates add-on is installed)
address a (if id_address is present in the grid)