SQLHelp sql数据库的DAL

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


namespace DAL
{
   public class SqlHelper
    {
       //连接字符
       public static string sqlconnstring = ConfigurationManager.ConnectionStrings["conn"].ConnectionString;

       #region 一个已经连接等待使用的对象
       /// <summary>
       /// 创建一个连接好并等待使用的对象
       /// </summary>
       /// <param name="conn">连接字符串</param>
       /// <param name="cmd">已经建立的SqlCommand对象</param>
       /// <param name="cmdType">连接类型（存储过程还是字符串）</param>
       /// <param name="sqlText">存储过程名或者SQL语句</param>
       /// <param name="parms">参数列表</param>
       public static void PrepareCommand(SqlConnection conn, SqlCommand cmd, CommandType cmdType, string sqlText, SqlParameter[] parms)
       {
           //判断数据库的连接状态
           if (conn.State != ConnectionState.Open)
           {
               conn.Open();
           }
           cmd.Connection = conn;//传递连接字符串
           cmd.CommandText = sqlText;//存储过程名或者SQL语句
           cmd.CommandType = cmdType;//连接类型

           if (parms != null)//如果参数列表不为空
           {
               foreach (var item in parms)
               {
                   cmd.Parameters.Add(item);
               }
           }
          

       } 
       #endregion

       #region ExecuteNonQuery
       /// <summary>
       /// 执行一个返回影响行数的SQLCommand命令
       /// </summary>
       /// <param name="connentionstring">连接字符串</param>
       /// <param name="cmdType">命令类型（存储过程，Sql语句）</param>
       /// <param name="sqlText">存储过程名称，或者Sql语句</param>
       /// <param name="parms">参数列表</param>
       /// <returns>返回数据库中受到影响的行数</returns>
       public static int ExecuteNonQuery(string connentionstring, CommandType cmdType, string sqlText, SqlParameter[] parms)
       {
           SqlCommand cmd = new SqlCommand();
           try
           {
               using (SqlConnection conn = new SqlConnection(connentionstring))
               {
                   PrepareCommand(conn, cmd, cmdType, sqlText, parms);
                   int value = cmd.ExecuteNonQuery();
                   return value;
               }
           }
           catch (Exception e)
           {
               throw e;
           }
       } 
       #endregion

       #region ExecuteReader
       /// <summary>
       /// 一个顺序只读的SqlCommand对象
       /// </summary>
       /// <param name="connectionString">连接字符串</param>
       /// <param name="cmdType">连接类型（存储过程，或者SQL语句）</param>
       /// <param name="sqlText">存储过程名或者SQL语句</param>
       /// <param name="parms">数组话的参数列表</param>
       /// <returns>返回 一个SqlDataReader类型的结果集</returns>
       public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string sqlText, SqlParameter[] parms)
       {
               SqlCommand cmd = new SqlCommand();
               SqlConnection conn = new SqlConnection(connectionString);
           try
           {
               PrepareCommand(conn, cmd, cmdType, sqlText, parms);
               SqlDataReader sdr = cmd.ExecuteReader();
               return sdr;
           }
           catch 
           {
               conn.Close();
               throw;
           }
       } 
       #endregion

       #region ExecuteScalar
       /// <summary>
       /// 执行一个返还第一行第一列的SqlCommand
       /// </summary>
       /// <param name="connectionString">连接字符串</param>
       /// <param name="cmdtype">连接类型（存储过程，SQL语句）</param>
       /// <param name="sqltext">存储过程名或者需要执行的SQL语句</param>
       /// <param name="parms">参数列表</param>
       /// <returns>返还一个Object 类型的值，使用过程中需要做类型转换</returns>
       public static object ExecuteScalar(string connectionString, CommandType cmdtype, string sqltext, SqlParameter[] parms)
       {
           SqlCommand cmd = new SqlCommand();
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                PrepareCommand(conn, cmd, cmdtype, sqltext, parms);
                Object obj = cmd.ExecuteScalar();
                return obj;
            }
       } 
       #endregion

       #region ExecuteDataset
       /// <summary>
       /// 执行一个返回DataSet集
       /// </summary>
       /// <param name="connectionString">连接字符串</param>
       /// <param name="cmdType">连接类型（存储过程，SQL语句）</param>
       /// <param name="sqltext">需要执行的SQL语句或存储过程名</param>
       /// <param name="parms">参数列表</param>
       /// <returns>返回一个DataSet集</returns>
       public static DataSet ExecuteDataset(string connectionString, CommandType cmdType, string sqltext, SqlParameter[] parms)
       {
           SqlCommand cmd = new SqlCommand();
           using (SqlConnection conn = new SqlConnection(connectionString))
           {
               PrepareCommand(conn, cmd, cmdType, sqltext, parms);
               using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
               {
                   DataSet ds = new DataSet();
                   sda.Fill(ds);
                   return ds;
               }
           }
       }
       #endregion

   }
}