如何通过主键从数据库提取数据，在Delphi中实现胜者姓名写入tblGames

我有一个包含tblGames和tblPlayers两个表的数据库，想要仅通过ID（主键）提取玩家的姓名。我已经梳理出逻辑：判断比赛胜负得到胜者ID，再从tblPlayers中获取该ID对应的姓名与姓氏，组合为WinnerName后写入tblGames的Winner列。但我对Delphi和数据库操作不太熟悉，没法正确实现这个逻辑，附上我的逻辑代码和Delphi代码片段，寻求解决方法。

梳理的逻辑代码 #

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

Delphi代码片段 #

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;

解决方法 #

要获取WinnerName，可以通过查询tblPlayers表匹配胜者ID，下面提供两种常用实现方式：

方式一：用TTable的Locate方法查找 #

BEGIN
    // 保留原有的平局与胜者ID判断逻辑
    var P1ScoreInt, P2ScoreInt: Integer;
    // 用TryStrToInt避免非数字输入导致崩溃
    if not (TryStrToInt(P1_Score, P1ScoreInt) and TryStrToInt(P2_Score, P2ScoreInt)) then
    begin
        ShowMessage('分数输入无效，请输入数字');
        Exit;
    end;

    Draw := (P1ScoreInt = P2ScoreInt);
    if P1ScoreInt > P2ScoreInt then
        winnerID := P1_ID
    else
        winnerID := P2_ID;

    with dmTournament do
    begin
        var WinnerName: string;
        if not Draw then
        begin
            var WinnerIDInt: Integer;
            if TryStrToInt(winnerID, WinnerIDInt) and tblPlayers.Locate('ID', WinnerIDInt, [loCaseInsensitive]) then
            begin
                // 替换为你实际的姓名、姓氏字段名
                WinnerName := tblPlayers['FirstName'].AsString + ' ' + tblPlayers['Surname'].AsString;
            end
            else
            begin
                WinnerName := '未知玩家';
            end;
        end
        else
        begin
            WinnerName := '平局'; // 平局场景可根据业务需求调整内容
        end;

        // 插入比赛记录
        tblGames.Insert;
        tblGames['Player1_Id'] := P1ScoreInt;
        tblGames['Player2_ID'] := P2ScoreInt;
        tblGames['Player1_score'] := P1ScoreInt;
        tblGames['Player2_Score'] := P2ScoreInt;
        tblGames['Draw'] := Draw;
        tblGames['Winner'] := WinnerName;
        tblGames.Post;
    end;
END;

方式二：用SQL查询获取姓名 #

如果更习惯SQL操作，可以用查询语句直接获取：

BEGIN
    // 保留原有的平局与胜者ID判断逻辑
    var P1ScoreInt, P2ScoreInt: Integer;
    if not (TryStrToInt(P1_Score, P1ScoreInt) and TryStrToInt(P2_Score, P2ScoreInt)) then
    begin
        ShowMessage('分数输入无效，请输入数字');
        Exit;
    end;

    Draw := (P1ScoreInt = P2ScoreInt);
    if P1ScoreInt > P2ScoreInt then
        winnerID := P1_ID
    else
        winnerID := P2_ID;

    with dmTournament do
    begin
        var WinnerName: string;
        if not Draw then
        begin
            var WinnerIDInt: Integer;
            if TryStrToInt(winnerID, WinnerIDInt) then
            begin
                // 假设使用ADOQuery组件，替换为你实际的查询组件
                with ADOQuery1 do
                begin
                    Close;
                    SQL.Text := Format('SELECT FirstName, Surname FROM tblPlayers WHERE ID = %d', [WinnerIDInt]);
                    Open;
                    if not Eof then
                        WinnerName := FieldByName('FirstName').AsString + ' ' + FieldByName('Surname').AsString
                    else
                        WinnerName := '未知玩家';
                    Close;
                end;
            end
            else
            begin
                WinnerName := '未知玩家';
            end;
        end
        else
        begin
            WinnerName := '平局';
        end;

        // 插入比赛记录
        tblGames.Insert;
        tblGames['Player1_Id'] := P1ScoreInt;
        tblGames['Player2_ID'] := P2ScoreInt;
        tblGames['Player1_score'] := P1ScoreInt;
        tblGames['Player2_Score'] := P2ScoreInt;
        tblGames['Draw'] := Draw;
        tblGames['Winner'] := WinnerName;
        tblGames.Post;
    end;
END;

注意事项 #

• 请将代码中的FirstName、Surname、ID替换为你数据库表中实际的字段名。
• 平局场景下Winner字段的内容可根据业务需求调整，比如设为空字符串。
• 始终用TryStrToInt替代StrToInt，避免非数字输入导致程序崩溃。

内容的提问来源于stack exchange，提问作者KindHeliCoptr