Question

所以我有一个具有多列唯一约束的数据库。显然要防止重复。在调试我的应用程序时，我的控制台完全被MySql.Data.MySqlClient.MySqlException s

填充

有没有办法压制这些，因为这是数据库的预期功能？抓住异常似乎并没有做到。它将根据我的catch(MySqlException e)语句处理它，但仍会在控制台中显示MySql.Data.MySqlClient.MySqlException。

这是我的代码：

public void InsertNewTeamHistory(TeamHistoryRow teamHistoryRow)
    {
        //open connection
        if (this.OpenConnection)
        {
            try
            {
                var query =
                    "INSERT INTO teamhistory(MatchURL, Date, TeamOne, TeamOneScore, TeamTwo, TeamTwoScore, Map, Event, Outcome) " +
                    "VALUES(?MatchURL, ?Date, ?TeamOne, ?TeamOneScore, ?TeamTwo, ?TeamTwoScore, ?Map, ?Event, ?Outcome)";

                //create command and assign the query and connection from the constructor
                using (var cmd = new MySqlCommand(query, _connection))
                {
                    if (cmd.Connection.State == ConnectionState.Open)
                    {
                        cmd.Parameters.Add("?MatchURL", MySqlDbType.VarChar).Value = teamHistoryRow.MatchUrl;
                        cmd.Parameters.Add("?Date", MySqlDbType.Date).Value = teamHistoryRow.Date;
                        cmd.Parameters.Add("?TeamOne", MySqlDbType.VarChar).Value = teamHistoryRow.TeamOne;
                        cmd.Parameters.Add("?TeamOneScore", MySqlDbType.Int32).Value = teamHistoryRow.TeamOneScore;
                        cmd.Parameters.Add("?TeamTwo", MySqlDbType.VarChar).Value = teamHistoryRow.TeamTwo;
                        cmd.Parameters.Add("?TeamTwoScore", MySqlDbType.Int32).Value = teamHistoryRow.TeamTwoScore;
                        cmd.Parameters.Add("?Map", MySqlDbType.VarChar).Value = teamHistoryRow.Map;
                        cmd.Parameters.Add("?Event", MySqlDbType.VarChar).Value = teamHistoryRow.Event;
                        cmd.Parameters.Add("?Outcome", MySqlDbType.VarChar).Value = teamHistoryRow.Outcome;

                        //Execute command
                        cmd.ExecuteNonQuery();

                        //close connection
                        this.CloseConnection();
                    }
                    else
                    {
                        throw new Exception("Failed - Connection to the DB NOT open.");
                    }
                }
            }
            catch (MySqlException e)
            {
                switch (e.Number)
                {
                    case 1062:
                        Console.WriteLine("Found Duplicate TeamHistoryRow, Not Inserting.");
                        break;
                    case 0:
                        Console.WriteLine("Well, we fucked up.");
                        break;
                    default:
                        throw;
                }
            }
            finally
            {
                try
                {
                    this.CloseConnection();
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex);
                }
            }
        }
    }

Answer 1

MySql有一个简单易用的功能，可以在您的语句中添加一条关于在找到重复键时该怎么做的规则。

INSERT INTO ..... ON DUPLICATE KEY UPDATE .....

因此您的查询语句可以重写为

INSERT INTO teamhistory(MatchURL, Date, TeamOne, TeamOneScore, TeamTwo, 
                       TeamTwoScore, Map, Event, Outcome) 
                       VALUES(?MatchURL, ?Date, ?TeamOne, 
                       ?TeamOneScore, ?TeamTwo, ?TeamTwoScore, 
                       ?Map, ?Event, ?Outcome) 
ON DUPLICATE KEY UPDATE MatchUrl = ?MatchUrl

这假设字段MatchUrl是触发重复异常的键。因此，当检测到重复键时，sql执行UPDATE更改表中的任何内容

通过标准化的command MERGE

，其他数据库系统也可以使用相同的逻辑

如何抑制MySql.Data.MySqlClient.MySqlException重复条目

1 个答案: