Database create Player

Hello i started to create a Mysql Database
now im in struggle to create a new Player i want that every Account create maximal 4 Players.

I started to send from Client to Server a Trigger with the Input Nodes Account ID (Steam) and the choosen Player Name then
the Server look on the Database how many Rows exist with the Account ID if he get < 4 back he create a new Player.
now i have the Problem that i cant get the Account Name and Player Name from the beginning that i can Create that Player with the choosen Name

i hope u can understand what i want to do :S

Look the Picture to see how i set this up: