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我试图让服务器从 SQL 数据库中读取 int 'rank'，但是我得到“使用未分配的局部变量”，因为它不会读取 'rank'，直到它应该在 while 语句中设置，但是我无法将其移出，因为它在进入 try and catch 之前不会执行 SQL 查询。

特别是这里：

using (var rdr = cmd.ExecuteReader())
            {
                while (rdr.Read())
                rank = rdr.GetInt32("rank");
            }

完整代码：

class Ban : ICommand
{
    public string Command { get { return "ban"; } }
    public int RequiredRank { get { return 3; } }

    public void Execute(Player player, string[] args)
    {
        int rank;
        string name = "'" + args[0] + "'";
        if (args.Length == 0)
        {
            player.SendHelp("Usage: /ban <username>");
        }
        try
        {
            using (Database dbx = new Database())
            {
                var cmd = dbx.CreateQuery();
                cmd.CommandText = "SELECT rank FROM accounts where name=@name";
                cmd.Parameters.AddWithValue("@name", name);
                cmd.ExecuteNonQuery();
                using (var rdr = cmd.ExecuteReader())
                {
                    while (rdr.Read())
                    rank = rdr.GetInt32("rank");
                }
                Console.Write("{0} ({1}) tried to ban {2}({3})", player.Name, player.Client.Account.Rank, name, rank);
                 if (rank < player.Client.Account.Rank)
                {
                    var cmda = dbx.CreateQuery();
                    cmda.CommandText = "UPDATE accounts SET banned=1, rank=0 WHERE name=@name";
                    cmda.Parameters.AddWithValue("@name", args[0]);
                    if (cmda.ExecuteNonQuery() == 0)
                    {
                        player.SendInfo("Could not ban");
                    }
                    else
                    {
                        foreach (var i in player.Owner.Players)
                        {
                            if (i.Value.nName.ToLower() == args[0].ToLower().Trim())
                            {
                                i.Value.Client.Disconnect();
                                player.SendInfo("Account successfully Banned");
                                Console.ForegroundColor = ConsoleColor.Yellow;
                                Console.Out.WriteLine(args[0] + " was Banned.");
                                Console.ForegroundColor = ConsoleColor.White;
                            }
                        }
                    }
                }
                 else if (rank >= player.Client.Account.Rank)
                    player.SendInfo("Could not ban");
            }
        }
        catch
        {
            player.SendInfo("Could not ban");
        }
    }
}
4

2 回答 2

1

编译器警告您，该变量在您使用它时可能尚未分配。

using (var rdr = cmd.ExecuteReader())
{
   while (rdr.Read())
   rank = rdr.GetInt32("rank");
}

rdr.Read()可能会立即返回 false 并且不会发生对 rank 的分配。

初始化rank你声明它的地方，即：int rank = 0;

于 2013-10-13T05:10:57.347 回答
1 
using (var rdr = cmd.ExecuteReader())
        {
            while (rdr.Read())
            rank = rdr.GetInt32(0); //try to set index of rank
        }
于 2013-10-13T05:23:54.070 回答