how to extract data from a database using the primary key

Question

I am trying to extract the Name of a person out of my database, containing two tables, with only having the ID (primary key).

I am struggling to come up with a solution, although I do have notes that I've written and the logic seems to check out (to me at least).

if P1Score > P2Score
then winner := P1ID 
else winner := P2ID 

winner in tblGames = the ID of winner in tblPlayers

WinnerName := first name of Winner + surname of Winner in tblPlayers

So this is my logic, obviously it's missing a lot, but I can't seem to expand on it much more

I have the ID of the person from tblGames, but now I'm struggling to understand how to use that ID to extract the Name and Surname from my tblPlayers and assign it to a variable, so I can put it into the Winner Column of tblGames.

I have tried a few things using my own thought process, but I do not know enough about Delphi and databases to actually implement it correctly.

 BEGIN
    if (StrToInt(P1_score) - StrToInt(P2_score) = 0) then
    Draw := True
    else
    Draw:= False;

    if StrtoInt(P1_Score) > StrToInt(P2_Score) then
        winnerID := P1_ID
        else
        winnerID := P2_ID;

 with dmTournament do
      begin

    tblGames.Insert;
    tblGames['Player1_Id'] := StrToInt(P1_ID);
    tblGames['Player2_ID'] := StrToInt(P2_ID);
    tblGames['Player1_score'] := StrToInt(P1_Score);
    tblGames['Player2_Score'] := StrToInt(P2_Score);
    tblGames['Draw'] := Draw;
    tblGames['Winner'] := WinnerName;  //How do I get WinnerName(?) 
    tblGames.Post;
      end;
  END;

Answer 1

You don't need to do a lot of code. You can let MySQL engine do job for you. Execute the following quires in same order they appeared. This will update the table data as you want.

/* 1: Set all games to draw */
UPDATE Games SET draw = true;

/* 2: Update when Player1 is winner :*/
UPDATE Games, Players SET  
  Games.draw = false,
  Games.winner = CONCAT(Players.first_name, ' ', Players.last_name)
WHERE
  (Games.player1_score > Games.player2_score) AND (Games.player1_id=Players.ID);

/* 3: Update when Player2 is winner */
UPDATE Games, Players SET  
  Games.draw = false,
  Games.winner = CONCAT(Players.first_name, ' ', Players.last_name)
WHERE
  (Games.player2_score > Games.player1_score) AND (Games.player2_id=Players.ID);