-- drop dependencies
alter table product drop constraint if exists ck_product_uom;
-- apply alter tables
alter table purchase_order alter column all_loading_site set default false;
alter table purchase_order alter column all_unloading_site set default false;
-- apply post alter
alter table product add constraint ck_product_uom check ( uom in ('KG','CFT','TON','LTR','NUMBER','MTR','BOX','CUM','PACKET','ALL','NOS','LITER'));