Question

我有一个允许我在MySQL数据库上运行查询的泛型类。

我在这个类中看到的唯一问题是它打开连接运行查询并关闭连接。

现在，我需要能够

START TRANSACTION;
SELECT ...
INSERT INTO table1...
INSERT INTO table2...
INSERT INTO table3...
如果以上所有查询均有效，则COMMIT;无法ROLLBACK;

是的，我需要一个事务，我需要确保所有查询都运行100％，或者我需要在重新开始之前回滚并更正错误。

如何修改我的课程以允许我处理上述步骤？

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using MySql.Data.MySqlClient;
using System.Windows.Forms;


namespace RM
{
    public class dbConnetion
    {
        //private OdbcConnection conn; 
        private static readonly string mServer = "localhost";
        private static readonly string mDatabase = "my_db_name";
        private static readonly string mUid = "my_db_user";
        private static readonly string mPassword = "my_user_password";
        private static readonly string mPort = "3306";
        private string conn_string = String.Format("server={0};user={1};database={2};port={3};password={4};", mServer, mUid, mDatabase, mPort, mPassword);


        public string SYSTEM_NAME { get; set; }

        public dbConnetion()
        {
            Initilize_System_Settings();
        }

        // query the data base
        public IEnumerable<T> getData<T>(string query, List<MySqlParameter> pars, Func<IDataRecord, T> transform)
        {
            using (var conn = new MySqlConnection(conn_string))
            using (var cmd = new MySqlCommand(query, conn))
            {
                if (pars != null)
                {
                    foreach (MySqlParameter p in pars)
                    {
                        cmd.Parameters.Add(p);
                    }
                }

                conn.Open();

                using (var rdr = cmd.ExecuteReader())
                {

                    while (rdr.Read())
                    {
                        yield return transform(rdr);
                    }
                }

                conn.Close();
            }
        }

        // query the data base
        public T getValue<T>(string query, List<MySqlParameter> pars)
        {
            T value;
            using (var conn = new MySqlConnection(conn_string))
            using (var cmd = new MySqlCommand(query, conn))
            {

                if (pars != null)
                {
                    foreach (MySqlParameter p in pars)
                    {
                        cmd.Parameters.Add(p);
                    }
                }


                try
                {
                    conn.Open();
                    object rawValue = cmd.ExecuteScalar();

                    if (rawValue != null)
                    {
                        value = (T)Convert.ChangeType(rawValue, typeof(T));
                    }
                    else
                    {
                        value = default(T);
                    }

                }
                catch (Exception ex)
                {

                    Common.Alert(ex.ToString(), "SQL Error");
                    value = default(T);

                }
                finally
                {
                    conn.Close();
                }

            }

            return value;
        }

        public bool processQuery(string strSQL, List<MySqlParameter> pars)
        {
            bool toReturn = true;
            using (var conn = new MySqlConnection(this.conn_string))
            using (var cmd = new MySqlCommand(strSQL, conn))
            {

                foreach (MySqlParameter param in pars)
                {
                    cmd.Parameters.Add(param);
                }

                try
                {
                    conn.Open();
                    cmd.ExecuteNonQuery();
                }
                catch (MySqlException ex)
                {
                    Common.Alert(ex.ToString(), "SQL Error");
                    toReturn = false;
                }
                finally
                {
                    conn.Close();
                }
            }

            return toReturn;
        }
    }
}

我的第一个想法是在getData方法中添加一个新参数，以便在有开放式交易时允许我不打开/关闭连接，例如

// query the data base
        public IEnumerable<T> getData<T>(string query, List<MySqlParameter> pars, Func<IDataRecord, T> transform, bool inTransaction = false)
        {
            using (var conn = new MySqlConnection(conn_string))
            using (var cmd = new MySqlCommand(query, conn))
            {
                if (pars != null)
                {
                    foreach (MySqlParameter p in pars)
                    {
                        cmd.Parameters.Add(p);
                    }
                }
                if(! inTransaction){
                    conn.Open();
                }
                using (var rdr = cmd.ExecuteReader())
                {

                    while (rdr.Read())
                    {
                        yield return transform(rdr);
                    }
                }
                if(! inTransaction){
                    conn.Close();
                }
            }
        }

但我认为由于using声明

Answer 1

trans = Conn.BeginTransaction();
trans.Commit();
trans.Rollback();

Cannot access SqlTransaction object to rollback in catch block

Answer 2

您必须确定从何处开始和结束交易，

using (var conn = new MySqlConnection(conn_string))
{
    var tx = conn.BeginTransaction();
    try
    {
        using (var cmd1 = new MySqlCommand(query1, conn))
        {
           cmd1.Transaction = tx;
           //do cmd 1 stuff here
        }

        using (var cmd2 = new MySqlCommand(query2, conn))
        {
           cmd2.Transaction = tx;
           //do cmd 1 stuff here
        }

       //do other commands....

       tx.Commit(); //or Rollback() based on results
    }
    catch (Exception ex)
    {
       tx.Rollback();
       throw ex;
    }
}

如何启动数据库事务，在MySQL上运行多个查询然后使用c＃提交或回滚？

2 个答案: