sqlhelper

       最近在为机房收费系统个人版做准备，其中有个神器sqlhelper，感觉它实在是太强大了，在此把代码和大家分享下。

     为了方便维护，我们在Web.config中写连接数据库的字符串，代码如下：     

<connectionStrings>
    <add name="connstr"  connectionString="server=(local);database = newsstem; uid = sa;pwd=123456"/>
</connectionStrings>

      sqlhelper类，它有4种功能，分别是执行不带参数的查询、执行不带参数的增删改、执行带参数的查询、执行带参数的增删改。代码如下：

/*
 *创建人：屈文哲
 *创建时间：2013-12-23
 *说明：数据库的助手类
 *版权声明：信息技术提高班
 */
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace DAL
{
    public class SQLHelper
    {
        private SqlConnection conn = null;
        private SqlCommand cmd = null;
        private SqlDataReader sdr = null;
        public SQLHelper()
        {
            string connStr = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
            conn = new SqlConnection(connStr);
        }

        private SqlConnection GetConn()
        {
            if (conn.State == ConnectionState.Closed)
            {
                conn.Open();
            }
            return conn;
        }

        ///<summary>
        ///执行不带参数的增删改SQL语句或存储过程
        /// </summary>
        /// <param name="cmdText">增删改SQL语句或存储过程</param>
        /// <param name="ct">命令类型</param>
        /// <returns></returns>
        public int ExecuteNonQuery(string cmdText,CommandType ct)
        {
            int res;
            try
            {
                cmd = new SqlCommand(cmdText, GetConn());
                cmd.CommandType = ct;
                res = cmd.ExecuteNonQuery();
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (conn.State == ConnectionState.Open)
                {
                    conn.Close();
                }
            }
            return res;
        }

        ///<summary>
        ///执行不带参数的查询SQL语句或存储过程
        /// </summary>
        /// <param name="cmdText">查询SQL语句或存储过程</param>
        /// <param name="ct">命令类型</param>
        /// <returns></returns>
        public DataTable ExecuteQuery(string cmdText,CommandType ct)
        {
            DataTable dt = new DataTable();
            cmd = new SqlCommand(cmdText, GetConn());
            cmd.CommandType = ct;
            using (sdr = cmd.ExecuteReader(CommandBehavior.CloseConnection))
            {
                dt.Load(sdr);
            }
            return dt;
        }

        ///<summary>
        ///执行带参数的增删改SQL语句或存储过程
        /// </summary>
        /// <param name="cmdText">增删改SQL语句或存储过程</param>
        /// <param name="ct">命令类型</param>
        /// <returns></returns>
        public int ExecuteNonQuery(string cmdText, SqlParameter[] paras,CommandType ct)
        {
            int res;
            using (cmd = new SqlCommand(cmdText, GetConn()))
            {
                cmd.CommandType = ct;
                cmd.Parameters.AddRange(paras);
                res = cmd.ExecuteNonQuery();
            }
            return res;
        }

        ///<summary>
        ///执行带参数的查询SQL语句或存储过程
        /// </summary>
        /// <param name="cmdText">查询SQL语句或存储过程</param>
        /// <param name="paras">参数集合</param>
        /// <param name="ct">命令类型</param>
        /// <returns></returns>
        public DataTable ExecuteQuery(string cmdText, SqlParameter[] paras,CommandType ct)
        {
            DataTable dt = new DataTable();
            cmd = new SqlCommand(cmdText, GetConn());
            cmd.CommandType = ct;
            cmd.Parameters.AddRange(paras);
            using (sdr = cmd.ExecuteReader(CommandBehavior.CloseConnection))
            {
                dt.Load(sdr);
            }
            return dt;
        }
    }

}

      定义好sqlhelper类，我们就能在D层的各种DAO类中方便的执行SQL语句。希望能对大家有所帮助。