MySqlHelper

using System;
using System.Data;
using MySql.Data;
using MySql.Data.MySqlClient;

namespace DBUtility
{
    /// <summary>
    /// 基于MySQL的数据层基类
    /// </summary>
    public abstract class MySqlHelper
    {
        #region PrepareCommand
        /// <summary>
        /// Command预处理
        /// </summary>
        /// <param name="conn">MySqlConnection对象</param>
        /// <param name="trans">MySqlTransaction对象，可为null</param>
        /// <param name="cmd">MySqlCommand对象</param>
        /// <param name="cmdType">CommandType，存储过程或命令行</param>
        /// <param name="cmdText">SQL语句或存储过程名</param>
        /// <param name="cmdParms">MySqlCommand参数数组，可为null</param>
        private static void PrepareCommand(MySqlConnection conn, MySqlTransaction trans, MySqlCommand cmd, CommandType cmdType, string cmdText, MySqlParameter[] cmdParms)
        {
            if (conn.State != ConnectionState.Open)
                conn.Open();

            cmd.Connection = conn;
            cmd.CommandText = cmdText;

            if (trans != null)
                cmd.Transaction = trans;

            cmd.CommandType = cmdType;

            if (cmdParms != null)
            {
                foreach (MySqlParameter parm in cmdParms)
                    cmd.Parameters.Add(parm);
            }
        }
        #endregion

        #region ExecuteNonQuery
        /// <summary>
        /// 执行命令
        /// </summary>
        /// <param name="connectionString">数据库连接字符串</param>
        /// <param name="cmdType">命令类型（存储过程或SQL语句）</param>
        /// <param name="cmdText">SQL语句或存储过程名</param>
        /// <param name="cmdParms">MySqlCommand参数数组</param>
        /// <returns>返回受引响的记录行数</returns>
        public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText, params MySqlParameter[] cmdParms)
        {
            MySqlCommand cmd = new MySqlCommand();

            using (MySqlConnection conn = new MySqlConnection(connectionString))
            {
                PrepareCommand(conn, null, cmd, cmdType, cmdText, cmdParms);
                int val = cmd.ExecuteNonQuery();
                cmd.Parameters.Clear();
                return val;
            }
        }

        /// <summary>
        /// 执行命令
        /// </summary>
        /// <param name="conn">Connection对象</param>
        /// <param name="cmdType">命令类型（存储过程或SQL语句）</param>
        /// <param name="cmdText">SQL语句或存储过程名</param>
        /// <param name="cmdParms">MySqlCommand参数数组</param>
        /// <returns>返回受引响的记录行数</returns>
        public static int ExecuteNonQuery(MySqlConnection conn, CommandType cmdType, string cmdText, params MySqlParameter[] cmdParms)
        {
            MySqlCommand cmd = new MySqlCommand();

            PrepareCommand(conn, null, cmd, cmdType, cmdText, cmdParms);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }

        /// <summary>
        /// 执行事务
        /// </summary>
        /// <param name="trans">MySqlTransaction对象</param>
        /// <param name="cmdType">命令类型（存储过程或SQL语句）</param>
        /// <param name="cmdText">SQL语句或存储过程名</param>
        /// <param name="cmdParms">MySqlCommand参数数组</param>
        /// <returns>返回受引响的记录行数</returns>
        public static int ExecuteNonQuery(MySqlTransaction trans, CommandType cmdType, string cmdText, params MySqlParameter[] cmdParms)
        {
            MySqlCommand cmd = new MySqlCommand();

            PrepareCommand(trans.Connection, trans, cmd, cmdType, cmdText, cmdParms);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }
        #endregion

        #region ExecuteScalar
        /// <summary>
        /// 执行命令，返回第一行第一列的值
        /// </summary>
        /// <param name="connectionString">数据库连接字符串</param>
        /// <param name="cmdType">命令类型（存储过程或SQL语句）</param>
        /// <param name="cmdText">SQL语句或存储过程名</param>
        /// <param name="cmdParms">MySqlCommand参数数组</param>
        /// <returns>返回Object对象</returns>
        public static object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText, params MySqlParameter[] cmdParms)
        {
            MySqlCommand cmd = new MySqlCommand();

            using (MySqlConnection connection = new MySqlConnection(connectionString))
            {
                PrepareCommand(connection, null, cmd, cmdType, cmdText, cmdParms);
                object val = cmd.ExecuteScalar();
                cmd.Parameters.Clear();
                return val;
            }
        }

        /// <summary>
        /// 执行命令，返回第一行第一列的值
        /// </summary>
        /// <param name="connectionString">数据库连接字符串</param>
        /// <param name="cmdType">命令类型（存储过程或SQL语句）</param>
        /// <param name="cmdText">SQL语句或存储过程名</param>
        /// <param name="cmdParms">MySqlCommand参数数组</param>
        /// <returns>返回Object对象</returns>
        public static object ExecuteScalar(MySqlConnection conn, CommandType cmdType, string cmdText, params MySqlParameter[] cmdParms)
        {
            MySqlCommand cmd = new MySqlCommand();

            PrepareCommand(conn, null, cmd, cmdType, cmdText, cmdParms);
            object val = cmd.ExecuteScalar();
            cmd.Parameters.Clear();
            return val;
        }
        #endregion

        #region ExecuteReader
        /// <summary>
        /// 执行命令或存储过程，返回MySqlDataReader对象
        /// 注意MySqlDataReader对象使用完后必须Close以释放MySqlConnection资源
        /// </summary>
        /// <param name="connectionString">数据库连接字符串</param>
        /// <param name="cmdType">命令类型（存储过程或SQL语句）</param>
        /// <param name="cmdText">SQL语句或存储过程名</param>
        /// <param name="cmdParms">MySqlCommand参数数组</param>
        /// <returns></returns>
        public static MySqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params MySqlParameter[] cmdParms)
        {
            MySqlCommand cmd = new MySqlCommand();
            MySqlConnection conn = new MySqlConnection(connectionString);

            try
            {
                PrepareCommand(conn, null, cmd, cmdType, cmdText, cmdParms);
                MySqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                cmd.Parameters.Clear();
                return dr;
            }
            catch
            {
                conn.Close();
                throw;
            }
        }
        #endregion

        #region ExecuteDataSet
        /// <summary>
        /// 执行命令或存储过程，返回DataSet对象
        /// </summary>
        /// <param name="connectionString">数据库连接字符串</param>
        /// <param name="cmdType">命令类型(存储过程或SQL语句)</param>
        /// <param name="cmdText">SQL语句或存储过程名</param>
        /// <param name="cmdParms">MySqlCommand参数数组(可为null值)</param>
        /// <returns></returns>
        public static DataSet ExecuteDataSet(string connectionString, CommandType cmdType, string cmdText, params MySqlParameter[] cmdParms)
        {
            MySqlCommand cmd = new MySqlCommand();

            using (MySqlConnection conn = new MySqlConnection(connectionString))
            {
                PrepareCommand(conn, null, cmd, cmdType, cmdText, cmdParms);
                MySqlDataAdapter da = new MySqlDataAdapter(cmd);
                DataSet ds = new DataSet();
                da.Fill(ds);
                conn.Close();
                cmd.Parameters.Clear();
                return ds;
            }
        }
        #endregion

    }
}