Thank you for the explanation.
So, it seems that method would just prevent any data from being INSERTd, whether it exists or not?
If the value for the text field for gamecode is equal to a value anywhere in the column "gamecode" under "disc_id", the form should be submit and the form's data will be INSERTd into the first table (opl_comp). If there is no match for the gamecode, then the data is not inserted.
How can SELECT accomplish that?