Change tracking

I'm about to try this, but I'd like some suggestions. I have a inventory table that an employee can update specific fields if they are incorrect, e.g. [INVENTORY_TABLE] fields example data part 1027P serial 543221-K qty 120 location G-5 I'd like to record what changed. Let's say they change the serial. One way would be a "static" changes table: [INVENTORY_CHANGES] fields example data old_part 1027P new_part 1027P old_serial 543221-K new_serial 543221-4 ... I'm thinking a better/more flexible solution would be [INVENTORY_CHANGES] inventory_id (FK to inventory table) field (in this case it would be serial, detected by comparing POST values to original values, but could be serial and qty/location) original 543221-K new_value 543221-4 Just curious as to other possible solutions or problems with these (probably the second one). Thanks, Mike Smith