c sharp database sql parameter encapsulates the writing of the class

The   sql   parameter of the database encapsulates the writing of the
class

using System; 
using System.Data; 
using System.Configuration; 
using System.Web; 
using System.Web.Security; 
using System.Web.UI; 
using System.Web.UI.WebControls; 
using System.Web.UI.WebControls.WebParts; 
using System.Web.UI.HtmlControls; 
using System.Data.SqlClient; 
using System.Text; 
namespace ChinaSite.classes 
{ 
    public class DbAccess 
    { 
        SqlConnection conn = null; 
        SqlCommand cmd = null; 
        public DbAccess() 
        { 
            // 
            // TODO:  Add the constructor logic here  
            // 
            conn = new SqlConnection(); 
            //conn.ConnectionString = "initial catalog=pubs;data source=.;user id=sa;password="; 
            //conn.ConnectionString = Convert.ToString(System.Configuration.ConfigurationSettings.AppSettings["datasource"]); 
            conn.ConnectionString = Convert.ToString(System.Configuration.ConfigurationManager.AppSettings["datasource"]); 
            cmd = new SqlCommand(); 
            cmd.Connection = conn; 
        } 
        /// <summary> 
        ///  Get data according to sql statements   
        /// </summary> 
        /// <param name="sql"></param> 
        /// <returns></returns> 
        public DataTable GetTable(string sql) 
        { 
            DataSet ds = new DataSet(); 

            try 
            { 
                cmd.CommandText = sql; 
                SqlDataAdapter da = new SqlDataAdapter(); 
                da.SelectCommand = cmd; 

                da.Fill(ds); 
            } 
            catch (Exception ex) 
            { 

                this.ShowError(ex.Message); 
                return null; 

            } 
            return ds.Tables[0] ?? new DataTable(); 
        } 

        /// <summary> 
        ///  Get data according to sql statements   With parameters   the   
        /// </summary> 
        /// <param name="sql"></param> 
        /// <param name="pas"></param> 
        /// <returns></returns> 
        public DataTable GetTable(string sql, params SqlParameter[] pas) 
        { 
            DataSet ds = new DataSet(); 
            try 
            { 
                cmd.CommandText = sql; 
                SqlDataAdapter da = new SqlDataAdapter(); 
                da.SelectCommand = cmd; 
                cmd.Parameters.Clear(); 

                foreach (SqlParameter temppa in pas) 
                { 
                    cmd.Parameters.Add(temppa); 
                } 


                da.Fill(ds); 
            } 
            catch (Exception ex) 
            { 

                this.ShowError(ex.Message); 
                return null; 
            } 
            return ds.Tables[0] ?? new DataTable(); 
        } 
        /// <summary> 
        ///  According to the sql Statement returns a new state  
        /// </summary> 
        /// <param name="sql"></param> 
        /// <returns></returns> 
        public bool GetState(string sql) 
        { 
            bool succ = false; 
            try 
            { 
                cmd.CommandText = sql; 
                conn.Open(); 
                succ = cmd.ExecuteNonQuery() > 0 ? (true) : (false); 
                conn.Close(); 
            } 
            catch (Exception ex) 
            { 

                this.ShowError(ex.Message); 
                return false; 
            } 
            return succ; 

        } 
        /// <summary> 
        ///  According to the sql Statement returns an argument to the new state   
        /// </summary> 
        /// <param name="sql">sql statements </param> 
        /// <param name="pas"> Set of parameters </param> 
        /// <returns></returns> 
        public bool GetState(string sql, params SqlParameter[] pas) 
        { 
            bool succ = false; 
            try 
            { 
                cmd.CommandText = sql; 
                cmd.Parameters.Clear(); 

                foreach (SqlParameter temppa in pas) 
                { 
                    cmd.Parameters.Add(temppa); 
                } 
                conn.Open(); 
                succ = cmd.ExecuteNonQuery() > 0 ? (true) : (false); 
                conn.Close(); 
            } 
            catch (Exception ex) 
            { 

                this.ShowError(ex.Message); 
                return false; 
            } 
            return succ; 

        } 
        /// <summary> 
        ///  According to the sql Statement returns the data for the first cell  
        /// </summary> 
        /// <param name="sql"></param> 
        /// <returns></returns> 
        public string GetOne(string sql) 
        { 
            string res = ""; 
            try 
            { 
                cmd.CommandText = sql; 
                conn.Open(); 
                res = cmd.ExecuteScalar() == null ? ("") : (Convert.ToString(cmd.ExecuteScalar())); 
                conn.Close(); 
            } 
            catch (Exception ex) 
            { 

                this.ShowError(ex.Message); 
                return null; 
            } 
            return res; 
        } 
        /// <summary> 
        ///   According to the sql Statement returns data with arguments for the first cell   
        /// </summary> 
        /// <param name="sql"></param> 
        /// <param name="pas"></param> 
        /// <returns></returns> 
        public string GetOne(string sql, params SqlParameter[] pas) 
        { 
            string res = ""; 
            try 
            { 
                cmd.CommandText = sql; 
                cmd.Parameters.Clear(); 

                foreach (SqlParameter temppa in pas) 
                { 
                    cmd.Parameters.Add(temppa); 
                } 
                conn.Open(); 
                res = cmd.ExecuteScalar() == null ? ("") : (Convert.ToString(cmd.ExecuteScalar())); 
                conn.Close(); 
            } 
            catch (Exception ex) 
            { 

                this.ShowError(ex.Message); 
                return null; 
            } 
            return res; 
        } 
        /// <summary> 
        ///  Return data DataReader 
        /// </summary> 
        /// <param name="sql"></param> 
        /// <returns></returns> 
        public SqlDataReader GetDataReader(string sql) 
        { 
            SqlDataReader dr = null; 
            try 
            { 
                conn.Open(); 
                cmd.CommandText = sql; 
                dr = cmd.ExecuteReader(); 
            } 
            catch (Exception ex) 
            { 

                this.ShowError(ex.Message); 
                return null; 
            } 
            return dr; 
        } 
        /// <summary> 
        ///  Return data DataReader With parameters   
        /// </summary> 
        /// <param name="sql"></param> 
        /// <param name="pas"></param> 
        /// <returns></returns> 
        public SqlDataReader GetDataReader(string sql, params SqlParameter[] pas) 
        { 
            SqlDataReader dr = null; 
            try 
            { 
                conn.Open(); 
                cmd.Parameters.Clear(); 

                foreach (SqlParameter temppa in pas) 
                { 
                    cmd.Parameters.Add(temppa); 
                } 

                cmd.CommandText = sql; 
                dr = cmd.ExecuteReader(); 
            } 
            catch (Exception ex) 
            { 

                this.ShowError(ex.Message); 
                return null; 
            } 
            return dr; 
        } 
        /// <summary> 
        ///  Open the connection  
        /// </summary> 
        public void OpenConn() 
        { 
            if (conn.State != ConnectionState.Open) 
            { 
                try 
                { 
                    conn.Open(); 
                } 
                catch (Exception ex) 
                { 

                    this.ShowError(ex.Message); 
                    return; 
                } 
            } 
        } 
        /// <summary> 
        ///  Close the connection  
        /// </summary> 
        public void CloseConn() 
        { 
            if (conn.State != ConnectionState.Closed) 
            { 
                try 
                { 
                    conn.Close(); 
                    cmd = null; 
                    conn = null; 
                } 
                catch (Exception ex) 
                { 

                    this.ShowError(ex.Message); 
                    return; 
                } 
            } 
        } 
        /// <summary> 
        ///  Error message pops up   
        /// </summary> 
        /// <param name="err"></param> 
        public void ShowError(string err) 
        { 
            System.Web.HttpContext.Current.Response.Write(Script(err, "")); 
        } 
        /// <summary> 
        ///  According to the information   
        /// </summary> 
        /// <param name="err"></param> 
        public void ShowMessage(string mes, string loc) 
        { 
            System.Web.HttpContext.Current.Response.Write(Script(mes, loc)); 
        } 
        /// <summary> 
        /// javascript The script  
        /// </summary> 
        /// <param name="mess"></param> 
        /// <param name="loc"></param> 
        /// <returns></returns> 
        public string Script(string mess, string loc) 
        { 
            StringBuilder sb = new StringBuilder(); 
            sb.Append("<script language='javascript'>"); 
            sb.Append("alter('"); 
            sb.Append(mess); 
            sb.Append("');"); 
            sb.Append(loc); 
            sb.Append("</script>"); 
            return sb.ToString(); 

        } 

    } 
}