SqlHelper类

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Configuration;

using System.Data.SqlClient;

using System.Data;



namespace DAL

{

    //写成静态类，当调用该类方法的时候不用在创建一个新对象

    public static class SqlHelper

    {

        private static readonly string constr = ConfigurationManager.ConnectionStrings["sql"].ConnectionString;

        /// <summary>

        /// 执行Insert，delete，Update时返回受影响的行数

        /// </summary>

        /// <param name="sql"></param>

        /// <param name="cmdType">SqlCommand命令类型（存储过程，T—Sql语句，等等）</param>

        /// <param name="pms"></param>

        /// <returns></returns>

        public static int ExecuteNonQuery(string sql, CommandType cmdType, params SqlParameter[] pms)

        {

            using (SqlConnection con=new SqlConnection(constr))

            {                

                using (SqlCommand cmd=new SqlCommand(sql,con))

                {                    

                    cmd.CommandType = cmdType;

                    if (pms!=null)

                    {

                        cmd.Parameters.AddRange(pms);

                    }

                    con.Open();

                    return cmd.ExecuteNonQuery();

                }

            }

        }

        /// <summary>

        /// 返回查询的首行首列

        /// </summary>

        /// <param name="sql"></param>

        /// <param name="cmdType">SqlCommand命令类型（存储过程，T—Sql语句，等等）</param>

        /// <param name="pms"></param>

        /// <returns></returns>

        public static object ExecuteScalar(string sql, CommandType cmdType, params SqlParameter[] pms)

        {

            using (SqlConnection con=new SqlConnection(constr))

            {

                using (SqlCommand cmd=new SqlCommand(sql,con))

                {

                    cmd.CommandType = cmdType;

                    if (pms!=null)

                    {

                        cmd.Parameters.AddRange(pms);

                    }

                    con.Open();

                    return cmd.ExecuteScalar();

                }

            }

        }

        /// <summary>

        /// 执行select语句时返回查询的数据

        /// </summary>

        /// <param name="sql"></param>

        /// <param name="cmdType">SqlCommand命令类型（存储过程，T—Sql语句，等等）</param>

        /// <param name="pms"></param>

        /// <returns></returns>

        public static SqlDataReader ExecuDataReader(string sql, CommandType cmdType, params SqlParameter[] pms)

        {

            //因为ExecuteReader是一行一行的读，所以必须保证con是连接的，因此这里不能用using自动释放资源

            SqlConnection con = new SqlConnection(constr);

            try

            {

                using (SqlCommand cmd = new SqlCommand(sql, con))

                {

                    cmd.CommandType = cmdType;

                    if (pms != null)

                    {

                        cmd.Parameters.AddRange(pms);

                    }

                    con.Open();

                    return cmd.ExecuteReader(CommandBehavior.CloseConnection);//当ExecuteReader方法发生异常时，CommandBehavior.CloseConnection会关闭连接

                }

            }

            catch (Exception)

            {

                if (con!=null)

                {

                    con.Close();

                    con.Dispose();                   

                }

                 throw;

            }

            

        }

        public static DataTable ExecuteDataTable(string sql, CommandType cmdType, params SqlParameter[] pms)

        {

            SqlDataAdapter da = new SqlDataAdapter(sql,constr);

            da.SelectCommand.CommandType = cmdType;

            if (pms!=null)

            {

                da.SelectCommand.Parameters.AddRange(pms);

            }

            DataTable dt = new DataTable();

            da.Fill(dt);

            return dt;

        }

    }

}