asp.net 数据库操作类

using System;
using System.Web;
using System.Data.SqlClient;
using System.Data;
using System.Configuration;

namespace op_db
{
/**//// <summary>
/// 专门用来处理与数据库的操作
/// </summary>
    public class db_class
    {
        成员#region 成员
        private SqlConnection conn=new SqlConnection();
        /**//// <summary>
        /// 私有成员
        /// </summary>
        private string _sql;
        /**//// <summary>
        /// 属性：数据库查询语句
        /// </summary>
        private string _er;
        public string er
        {
            get{return _er;}
            
        }
        public string sql
        {
            get{return _sql;}
            set{_sql=value;}
        }
        #endregion


        函数#region 函数

        /**//// <summary>
        /// 构造函数
        /// </summary>
        public db_class()
        {
            //
            // TODO: 在此处添加构造函数逻辑
            //
            conn.ConnectionString=System.Configuration.ConfigurationSettings.AppSettings["constr"].ToString();
        }
        /**//// <summary>
        /// 析构函数
        /// </summary>
        ~ db_class()
        {
            if (conn.State==ConnectionState.Open)
            conn.Close();
        }

        /**//// <summary>
        /// 打开数据库连接
        /// </summary>
        public void db_open()
        {
            try
            {
                if (conn.State==ConnectionState.Closed)
                {
                    conn.ConnectionString=System.Configuration.ConfigurationSettings.AppSettings["constr"].ToString();
                    conn.Open();
                }
            }
            catch(Exception ex)
            {
                //System.Web.HttpContext.Current.Response.Redirect(System.Configuration.ConfigurationSettings.AppSettings["conn_admin"].ToString());
                System.Web.HttpContext.Current.Response.Write(ex.Message);
                System.Web.HttpContext.Current.Response.End();
            }

        }

        /**//// <summary>
        /// 关闭数据库连接
        /// </summary>
        public void db_close()
        {
            if (conn.State==ConnectionState.Open){
                conn.Close();
                conn.Dispose();
            }
        }


        /**//// <summary>
        /// 执行非返回型查询语句
        /// </summary>
        /// <returns>是否执行成功</returns>
        public bool executesql()
        {
            SqlCommand cmd=new SqlCommand(_sql,conn);
            this.db_open();
            try
            {
                cmd.ExecuteNonQuery();
                this.db_close();
                return true;
            }
            catch(Exception ex)
            {
                this.db_close();
                System.Web.HttpContext.Current.Response.Write(ex.Message);
                System.Web.HttpContext.Current.Response.End();
                return false;
            }

        }

        /**//// <summary>
        /// 执行返回datareader的数据库查询
        /// </summary>
        /// <returns>datareader对象</returns>
        public SqlDataReader executereader()
        {
            SqlCommand cmd=new SqlCommand(_sql,conn);
            this.db_open();
            SqlDataReader dr;
            try
            {
                dr=cmd.ExecuteReader(CommandBehavior.CloseConnection);//参数表示关闭datagrid对象就会关闭connection对象
                if (dr.HasRows==true)
                {
                    return dr;
                }
                else
                {
                    _er="数据为空";
                    return null;
                }
            }
            catch
            {
                _er="语句错误";
                return null;
            }
        }


        /**//// <summary>
        /// 将sql语句返回为dataview
        /// </summary>
        /// <returns>dataview对象</returns>
        public DataView executedv()
        {
            System.Data.SqlClient.SqlDataAdapter da=new SqlDataAdapter(_sql,conn);
            DataSet ds=new DataSet();
            this.db_open();
            try
            {
                da.Fill(ds,"tb");
                DataView dv=new DataView(ds.Tables["tb"]);
                if (dv.Count>0)
                {
                    this.db_close();
                    return dv;
                }
                else
                {
                    this.db_close();
                    _er="数据出错";
                    return null;
                }
            }
            catch
            {
                _er="数据出错";
                return null;
            }
            finally
            {
                this.db_close();
            }
        }

        /**//// <summary>
        /// 将只返回一条记录的sql语句执行并且返回结果
        /// </summary>
        /// <param name="def">如果没有记录的话的默认值</param>
        /// <returns>返回结果为string</returns>
        
        public string sql2str(string def)
        {
            string rr="";
            SqlCommand cmd=new SqlCommand(_sql,conn);
            System.Data.SqlClient.SqlDataReader dr;
            this.db_open();
            try
            {
                dr=cmd.ExecuteReader(CommandBehavior.CloseConnection);
                if(dr.HasRows)
                {
                    dr.Read();
                    rr=dr[0].ToString();
                    dr.Close();
                    this.db_close();
                }
            }
            catch
            {
                rr="";
            }
            finally{this.db_close();}
            if(rr=="")
                rr=def;
            return rr;
        }


        /**//// <summary>
        /// 执行返回BOOL的存储过程
        /// </summary>
        /// <returns>是否执行成功</returns>
        public bool exepro()
        {
            this.db_open();
            SqlCommand cmd=new SqlCommand(_sql,conn);
            cmd.CommandType=CommandType.StoredProcedure;
            try
            {
                cmd.ExecuteNonQuery();
                this.db_close();
                return true;
            }
            catch
            {
                this.db_close();
                return false;
            }

        }
        #endregion
    }
}