using MySql.Data.MySqlClient;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Test.DBHelper
{
    /// <summary>
    /// MySql帮助类
    /// </summary>
    public class MySqlHelper
    {
        /// <summary>
        /// 默认连接字符串
        /// </summary>
        public static readonly string defaultConnection = ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;


        public static object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText, params MySqlParameter[] commandParameters)
        {
            MySqlCommand cmd = new MySqlCommand();

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

        public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText, params MySqlParameter[] commandParameters)
        {
            // Create a new MySql command
            MySqlCommand cmd = new MySqlCommand();

            //Create a connection
            using (MySqlConnection connection = new MySqlConnection(connectionString))
            {

                //Prepare the command
                PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);

                //Execute the command
                
                int val = cmd.ExecuteNonQuery();
                cmd.Parameters.Clear();
                return val;
            }
        }

        /// <summary>
        /// Internal function to prepare a command for execution by the database
        /// </summary>
        /// <param name="cmd">Existing command object</param>
        /// <param name="conn">Database connection object</param>
        /// <param name="trans">Optional transaction object</param>
        /// <param name="cmdType">Command type, e.g. stored procedure</param>
        /// <param name="cmdText">Command test</param>
        /// <param name="commandParameters">Parameters for the command</param>
        private static void PrepareCommand(MySqlCommand cmd, MySqlConnection conn, MySqlTransaction trans, CommandType cmdType, string cmdText, MySqlParameter[] commandParameters)
        {

            //Open the connection if required
            if (conn.State != ConnectionState.Open)
                conn.Open();

            //Set up the command
            cmd.Connection = conn;
            cmd.CommandText = cmdText;
            cmd.CommandType = cmdType;

            //Bind it to the transaction if it exists
            if (trans != null)
                cmd.Transaction = trans;

            // Bind the parameters passed in
            if (commandParameters != null)
            {
                foreach (MySqlParameter parm in commandParameters)
                    cmd.Parameters.Add(parm);
            }
        }

        /// <summary>
        /// 执行ＳＱＬ语句或者存储过程 ,返回参数dataset
        /// </summary>
        /// <param name="connection">要执行ＳＱＬ语句的连接</param>
        /// <param name="commandText">ＳＱＬ语句或者存储过程名</param>
        /// <param name="commandParameters">ＳＱＬ语句或者存储过程参数</param>
        /// <param name="commandType">ＳＱＬ语句类型</param>
        /// <param name="commandTimeout">超时时间</param>
        /// <returns>执行结果集</returns>
        public static DataSet ExecuteDataset(string connectionString, CommandType commandType, string commandText, params MySqlParameter[] commandParameters)
        {
            MySqlCommand cmd = new MySqlCommand();
            bool mustCloseConnection = false;
            using (MySqlConnection connection = new MySqlConnection(connectionString))
            {
                PrepareCommand(cmd, connection, null, commandType, commandText, commandParameters);
                using (MySqlDataAdapter da = new MySqlDataAdapter(cmd))
                {
                    DataSet ds = new DataSet();
                    da.Fill(ds);
                    cmd.Parameters.Clear();
                    if (mustCloseConnection)
                        connection.Close();
                    return ds;
                }
            }
        }
    }
}
