Question

我正在使用Sqlite3。

我有一个表'Team'，它有一个可以为空的'Player'列表。

每个'Player'都是一个唯一的id，它是另一个表'Player'的外键。

每个'团队'最多可以有10个玩家。

每个“玩家”的名字都是这样的：

"CREATE TABLE IF NOT EXISTS "
"Team"
"("
"TeamID varchar(64) PRIMARY KEY,"
"UserID varchar(64) NOT NULL,"
"League varchar(255) NOT NULL,"
"PlayerID_1 varchar(64),"
"PlayerID_2 varchar(64),"
"PlayerID_3 varchar(64),"
"PlayerID_4 varchar(64),"
"PlayerID_5 varchar(64),"
"PlayerID_6 varchar(64),"
"PlayerID_7 varchar(64),"
"PlayerID_8 varchar(64),"
"PlayerID_9 varchar(64),"
"PlayerID_10 varchar(64),"
"FOREIGN KEY (UserID) REFERENCES User(UserID),"
"FOREIGN KEY (PlayerID_1) REFERENCES Player(PlayerID),"
"FOREIGN KEY (PlayerID_2) REFERENCES Player(PlayerID),"
"FOREIGN KEY (PlayerID_3) REFERENCES Player(PlayerID),"
"FOREIGN KEY (PlayerID_4) REFERENCES Player(PlayerID),"
"FOREIGN KEY (PlayerID_5) REFERENCES Player(PlayerID),"
"FOREIGN KEY (PlayerID_6) REFERENCES Player(PlayerID),"
"FOREIGN KEY (PlayerID_7) REFERENCES Player(PlayerID),"
"FOREIGN KEY (PlayerID_8) REFERENCES Player(PlayerID),"
"FOREIGN KEY (PlayerID_9) REFERENCES Player(PlayerID),"
"FOREIGN KEY (PlayerID_10) REFERENCES Player(PlayerID)"
");";

我的问题是，如何轻松地将新的“播放器”插入表格？我需要一种方法迭代表中的每个当前'Player'，找到第一个NULL列。

我正在使用来自C的这个数据库接口，并且用一个查询将表放入内存并不是那么困难，在内存中迭代它以找到第一个NULL'Player'，并在那里插入新的，但这似乎效率极低！

另外，如果设计不好，请随意提出更好的设计！我仍然是数据库设计的新手。

Answer 1

我不会使用那种设计，如果你对你的桌子进行规范化以便你拥有＆＃34;播放器＆＃34;那会更好。表参考＆＃34;团队＆＃34;表告诉某个玩家属于哪个队伍。

然后，向团队添加新玩家只需向＆＃34;玩家＆＃34;添加新行。表

让玩家切换球队，甚至移除球员也更容易。

您可以从应用程序中控制每个团队10名玩家的限制（在添加新玩家之前，检查团队已有多少玩家）。

或者你可以创建一个触发器，如果在Player表中添加一行会导致团队中有超过10名玩家，则会引发错误。

 "CREATE TABLE IF NOT EXISTS "
 "Team"
 "("
 "TeamID varchar(64) PRIMARY KEY,"
 "UserID varchar(64) NOT NULL,"
 "League varchar(255) NOT NULL,"
 "FOREIGN KEY (UserID) REFERENCES User(UserID)"
 ");";

 "CREATE TABLE IF NOT EXISTS "
 "Player"
 "("
 "PlayerID varchar(64) PRIMARY KEY,"
 "TeamID varchar(64) NOT NULL,"
 "PlayerName varchar(255) NOT NULL,"
 "FOREIGN KEY (TeamID) REFERENCES Team(TeamID)"
 ");";

修改

如果同一个玩家可以在多个团队中，那么您需要第三个表来将玩家映射到团队。

然后，每个玩家只能存在一次，但是你可以通过在＆＃34; PlayerToTeam＆＃34;中添加多行来将同一玩家映射到多个团队。表

这样的事情：

"CREATE TABLE IF NOT EXISTS " "Team" "(" "TeamID varchar(64) PRIMARY KEY," "UserID varchar(64) NOT NULL," "League varchar(255) NOT NULL," "FOREIGN KEY (UserID) REFERENCES User(UserID)" ");"; "CREATE TABLE IF NOT EXISTS " "Player" "(" "PlayerID varchar(64) PRIMARY KEY," "PlayerName varchar(255) NOT NULL," ");"; "CREATE TABLE IF NOT EXISTS " "PlayerToTeam" "(" "PlayerID varchar(64) NOT NULL," "TeamID varchar(64) NOT NULL," "PRIMARY KEY (PlayerID, TeamID)," "FOREIGN KEY (PlayerID) REFERENCES Player(PlayerID)," "FOREIGN KEY (TeamID) REFERENCES Team(TeamID)" ");";

如何管理表中的外键列表？

1 个答案: