自己动手写SqlHelper类！

using System;

using System.Collections.Generic;

using System.Configuration;

using System.Data.SqlClient;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace WpfApplication1_dataset_离线数据集

{

    class SqlHelper

    {

        private static string connStr = ConfigurationManager.ConnectionStrings["dbConnstr"].ConnectionString;

        public static int ExecuteNonQuery(string sql)

        {

            using (SqlConnection conn = new SqlConnection(connStr))

            {

                conn.Open();

                using (SqlCommand cmd = conn.CreateCommand())

                {

                    cmd.CommandText = sql;

                    return cmd.ExecuteNonQuery();

                }

            }

        }

        public static object ExecuteScalar(string sql)

        {

            using (SqlConnection conn = new SqlConnection(connStr))

            {

                conn.Open();

                using (SqlCommand cmd = conn.CreateCommand())

                {

                    cmd.CommandText = sql;

                    return cmd.ExecuteScalar();

                }

            }

        }

    }

}