Field Validation

So here’s my question. I’m still researching the best answer.
If enter a name and date of birth in the form and click submit. I want that name and date to go against another table and if there is a match populate a field in the first table.
So here’s the word version.
If the player name and Date of birth from the team_form match the player name and date of birth in the player_form then I want the team_form.playerclass to get the value from the player_form.playerclass

Does that make sense ? and if so is it possible?