Common ADO Operation Access database

usingSystem;usingSystem.Collections.Generic;usingSystem.Text;usingSystem.Data;//usingSystem.Data.OleDb;//usingSystem.Drawing;//namespaceecolor{classControldbs {//defining a link string        PrivateOleDbConnection con; /// <summary>        ///constructor Function/// </summary>        /// <param name= "path" >Database Path</param>         PublicControldbs (stringpath) {Con=NewOleDbConnection (@"Provider=Microsoft.Jet.OLEDB.4.0;Data source="+path); }        /// <summary>        ///get SQL query data to data table/// </summary>        /// <param name= "SQL" >SQL statements</param>        /// <returns>Data Sheet</returns>         PublicDataTable getdatatable (stringSQL) {OleDbDataAdapter ADP=NewOleDbDataAdapter (SQL, con); Try{con.                Open (); DataTable DT=NewDataTable (); Adp.                Fill (DT); returnDT; }            Catch            {                return NULL; }            finally{con.            Close (); }        }        /// <summary>        ///get data to data set/// </summary>        /// <param name= "SQL" >SQL statements</param>        /// <returns>Data Set</returns>         PublicDataSet GetDataSet (stringSQL) {OleDbDataAdapter ADP=NewOleDbDataAdapter (SQL, con); Try{con.                Open (); DataSet DS=NewDataSet (); Adp.                Fill (DS); returnds; }            Catch            {                return NULL; }            finally{con.            Close (); }        }        /// <summary>        ///get data to DataReader/// </summary>        /// <param name= "SQL" >SQL statements</param>        /// <returns>DataReader</returns>         PublicOleDbDataReader Getdatareader (stringSQL) {OleDbCommand cmd=NewOleDbCommand (SQL, con); Try{con.                Open (); OleDbDataReader Dr=cmd.                ExecuteReader (); returnDr; }            Catch            {                return NULL; }        }        /// <summary>        ///returns the first column of the first row of the SQL query/// </summary>        /// <param name= "SQL" >SQL statements</param>        /// <returns>string of first column in first row</returns>         Public stringGetfirstvalue (stringSQL) {OleDbCommand cmd=NewOleDbCommand (SQL, con); Try{con.                Open (); stringStrchar =cmd. ExecuteScalar ().                ToString (); returnStrchar; }            Catch            {                return NULL; }            finally{con.            Close (); }        }        /// <summary>        ///Execute SQL statement/// </summary>        /// <param name= "SQL" >SQL statements</param>         Public voidRunsqlcmd (stringSQL) {OleDbCommand cmd=NewOleDbCommand (SQL, con); Try{con.                Open (); Cmd.            ExecuteNonQuery (); }            Catch            { }            finally{con.            Close (); }        }    }}

Common ADO Operation Access database