SqlHelper类的编写

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
using System.Data;
using System.Configuration;

namespace WpfApplication1
{
    public class SqlHelper
    {
        private static string connStr = ConfigurationManager.ConnectionStrings["dbConnStr"].ConnectionString;

        public static int ExecuteNonQuery(string sql,params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    //foreach (SqlParameter parm in parameters)
                    //{
                    //    cmd.Parameters.Add(parm);
                    //}
                    cmd.Parameters.AddRange(parameters);
                    return cmd.ExecuteNonQuery();
                }
            }
        }

        public static object ExecuteScalar(string sql,params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);
                    return cmd.ExecuteScalar();
                }
            }
        }

        /// <summary>
        ///  只用来执行查询结果比较少的sql
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static DataTable ExecuteDataTable(string sql,params SqlParameter[] parameters)
        {
            DataSet dataSet = new DataSet();
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);
                    SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                    adapter.Fill(dataSet);
                    return dataSet.Tables[0];
                }
            }
        }

    }
}