(C#) ASP.NET Oracle Database Class

Using System.Data; 
Using System.Data.OracleClient;

using System;
using System.Data;
using System.Configuration;
using System.Collections;
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.OracleClient;

public partial class clsDatabase : System.Web.UI.Page
{
    private OracleConnection objConn;
    private OracleCommand objCmd;
    private OracleTransaction Trans;
    private String strConnString;

    public clsDatabase()
    {
        strConnString = System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"];
    }

    public OracleDataReader QueryDataReader(String strSQL)
    {
        OracleDataReader dtReader;
        objConn = new OracleConnection();
        objConn.ConnectionString = strConnString;
        objConn.Open();

        objCmd = new OracleCommand(strSQL, objConn);
        dtReader = objCmd.ExecuteReader();
        return dtReader; //*** Return DataReader ***//
    }

    public DataSet QueryDataSet(String strSQL)
    {
        DataSet ds = new DataSet();
        OracleDataAdapter dtAdapter = new OracleDataAdapter();
        objConn = new OracleConnection();
        objConn.ConnectionString = strConnString;
        objConn.Open();

        objCmd = new OracleCommand();
        objCmd.Connection = objConn;
        objCmd.CommandText = strSQL;
        objCmd.CommandType = CommandType.Text;

        dtAdapter.SelectCommand = objCmd;
        dtAdapter.Fill(ds);
        return ds;   //*** Return DataSet ***//
    }

    public DataTable QueryDataTable(String strSQL)
    {
        OracleDataAdapter dtAdapter;
        DataTable dt = new DataTable();
        objConn = new OracleConnection();
        objConn.ConnectionString = strConnString;
        objConn.Open();

        dtAdapter = new OracleDataAdapter(strSQL, objConn);
        dtAdapter.Fill(dt);
        return dt; //*** Return DataTable ***//
    }

    public Boolean QueryExecuteNonQuery(String strSQL)
    {
        objConn = new OracleConnection();
        objConn.ConnectionString = strConnString;
        objConn.Open();

        try
        {
            objCmd = new OracleCommand();
            objCmd.Connection = objConn;
            objCmd.CommandType = CommandType.Text;
            objCmd.CommandText = strSQL;

            objCmd.ExecuteNonQuery();
            return true; //*** Return True ***//
        }
        catch (Exception)
        {
            return false; //*** Return False ***//
        }
    }


    public Object QueryExecuteScalar(String strSQL)
    {
        Object obj;
        objConn = new OracleConnection();
        objConn.ConnectionString = strConnString;
        objConn.Open();

        try
        {
            objCmd = new OracleCommand();
            objCmd.Connection = objConn;
            objCmd.CommandType = CommandType.Text;
            objCmd.CommandText = strSQL;

            obj = objCmd.ExecuteScalar();  //*** Return Scalar ***//
            return obj;
        }
        catch (Exception)
        {
            return null; //*** Return Nothing ***//
        }
    }

    public void TransStart()
    {
        objConn = new OracleConnection();
        objConn.ConnectionString = strConnString;
        objConn.Open();
        Trans = objConn.BeginTransaction(IsolationLevel.ReadCommitted);
    }


    public void TransExecute(String strSQL)
    {
        objCmd = new OracleCommand();
        objCmd.Connection = objConn;
        objCmd.Transaction = Trans;
        objCmd.CommandType = CommandType.Text;
        objCmd.CommandText = strSQL;
        objCmd.ExecuteNonQuery();
    }


    public void TransRollBack()
    {
        Trans.Rollback();
    }

    public void TransCommit()
    {
        Trans.Commit();
    }

    public void Close()
    {
        objConn.Close();
        objConn = null;
    }
}

<%@ Import Namespace="System.Data"%>
<%@ Import Namespace="System.Data.OracleClient"%>
<%@ Page Language="C#" Debug="true"%>

<script runat="server">
	
    clsDatabase clsDB = new clsDatabase();
    void Page_Load(object sender, EventArgs e)
    {
        myDataReader();
        myDataSet();
        myDataTable();
        myQueryExecuteScalar();
        myExecuteNonQuery();
        myExecuteTransaction();
    }


    //*** DataReader ***//
    void myDataReader()
    {
        String strSQL;
        OracleDataReader dtReader;
        strSQL = "SELECT * FROM customer ";
        dtReader = clsDB.QueryDataReader(strSQL);
        this.myDataGrid1.DataSource = dtReader;
        this.myDataGrid1.DataBind();

        //*** Bind Rows ***//
        /*
        if(dtReader.HasRows == true)
        {
            dtReader.Read();
            this.lblCustomerID.Text = dtReader["CustomerID"].ToString();
            this.lblName.Text = dtReader["Name"].ToString();
            this.lblEmail.Text = dtReader["Email"].ToString();
            this.lblCountryCode.Text = dtReader["CountryCode"].ToString();
            this.lblBudget.Text = dtReader["Budget"].ToString();
            this.lblUsed.Text = dtReader["Used"].ToString();
        }
        */

        clsDB.Close();
    }

    //*** DataSet ***//
    void myDataSet()
    {
        String strSQL;
        DataSet ds;
        strSQL = "SELECT * FROM customer ";
        ds = clsDB.QueryDataSet(strSQL);
        this.myDataGrid2.DataSource = ds.Tables[0].DefaultView;
        this.myDataGrid2.DataBind();

        //*** Bind Rows ***//
        if (ds.Tables[0].Rows.Count > 0)
        {
            this.lblCustomerID.Text = ds.Tables[0].Rows[0]["CustomerID"].ToString();
            this.lblName.Text = ds.Tables[0].Rows[0]["Name"].ToString();
            this.lblEmail.Text = ds.Tables[0].Rows[0]["Email"].ToString();
            this.lblCountryCode.Text = ds.Tables[0].Rows[0]["CountryCode"].ToString();
            this.lblBudget.Text = ds.Tables[0].Rows[0]["Budget"].ToString();
            this.lblUsed.Text = ds.Tables[0].Rows[0]["Used"].ToString();
        }
        clsDB.Close();
    }

    //*** DataTable ***//
    void myDataTable()
    {
        String strSQL;
        DataTable dt;
        strSQL = "SELECT * FROM customer ";
        dt = clsDB.QueryDataTable(strSQL);
        this.myDataGrid3.DataSource = dt;
        this.myDataGrid3.DataBind();

        //*** Bind Rows ***//
        if (dt.Rows.Count > 0)
        {
            this.lblCustomerID.Text = dt.Rows[0]["CustomerID"].ToString();
            this.lblName.Text = dt.Rows[0]["Name"].ToString();
            this.lblEmail.Text = dt.Rows[0]["Email"].ToString();
            this.lblCountryCode.Text = dt.Rows[0]["CountryCode"].ToString();
            this.lblBudget.Text = dt.Rows[0]["Budget"].ToString();
            this.lblUsed.Text = dt.Rows[0]["Used"].ToString();
        }
        clsDB.Close();
    }

    //*** Execute Scalar ***//
    void myQueryExecuteScalar()
    {
        String strSQL;
        strSQL = "SELECT MAX(Budget) FROM customer ";
        this.lblText.Text = clsDB.QueryExecuteScalar(strSQL).ToString();
        clsDB.Close();
    }

    //*** ExecuteNonQuery ***//
    void myExecuteNonQuery()
    {
        String strSQL1, strSQL2, strSQL3;

        //*** Insert ***//
        strSQL1 = "INSERT INTO customer (CustomerID,Name,Email,CountryCode,Budget,Used) " +
        " VALUES('C005','Weerachai Nukitram','[email protected]','TH','200000','100000')";
        if (clsDB.QueryExecuteNonQuery(strSQL1) == true)
        {
            //*** Condition Success ***//
        }
        else
        {
            //*** Condition Error ***//
        }
        clsDB.Close();

        //*** Update ***//
        strSQL2 = "UPDATE customer SET Budget = '3000000' WHERE CustomerID = 'C005' ";
        if (clsDB.QueryExecuteNonQuery(strSQL2) == true)
        {
            //*** Condition Success ***//
        }
        else
        {
            //*** Condition Error ***//
        }
        clsDB.Close();

        //*** Delete ***//
        strSQL3 = "DELETE FROM customer WHERE CustomerID = 'C005' ";
        if (clsDB.QueryExecuteNonQuery(strSQL3) == true)
        {
            //*** Condition Success ***//
        }
        else
        {
            //*** Condition Error ***//
        }
        clsDB.Close();
    }

    //*** Execute Transaction ***'
    void myExecuteTransaction()
    {
        String strSQL1, strSQL2, strSQL3;

        //*** Start Transaction ***//
        clsDB.TransStart();

        try
        {

            //*** Insert ***//
            strSQL1 = "INSERT INTO customer (CustomerID,Name,Email,CountryCode,Budget,Used) " +
            " VALUES('C005','Weerachai Nukitram','[email protected]','TH','200000','100000')";
            clsDB.TransExecute(strSQL1); //*** Execute Query 1 ***//

            //*** Update ***//
            strSQL2 = "UPDATE customer SET Budget = '3000000' WHERE CustomerID = 'C005' ";
            clsDB.TransExecute(strSQL2); //*** Execute Query 2 ***//

            //*** Delete ***//
            strSQL3 = "DELETE FROM customer WHERE CustomerID = 'C005' ";
            clsDB.TransExecute(strSQL3); //*** Execute Query 3 **//

            //*** Commit Transaction ***//
            clsDB.TransCommit();
        }
        catch (Exception)
        {
            //*** RollBack Transaction ***//
            clsDB.TransRollBack();
        }

        clsDB.Close();
    }


</script>
<html>
<head>
<title>ThaiCreate.Com ASP.NET - Database Class</title>
</head>
<body>
	<form id="form1" runat="server">
			<asp:DataGrid id="myDataGrid1" runat="server"></asp:DataGrid>
			<br>
			<br>
			<asp:DataGrid id="myDataGrid2" runat="server"></asp:DataGrid><br>
			<br>
			<asp:DataGrid id="myDataGrid3" runat="server"></asp:DataGrid><br>
			<table style="WIDTH: 300px" border="1">
				<tr>
					<td style="WIDTH: 93px">
						<asp:Label id="lblHeaderCustomerID" runat="server" Text="CustomerID"></asp:Label></td>
					<td style="WIDTH: 213px">
						<asp:Label id="lblCustomerID" runat="server"></asp:Label></td>
				</tr>
				<tr>
					<td style="WIDTH: 93px">
						<asp:Label id="lblHeaderName" runat="server" Text="Name"></asp:Label></td>
					<td style="WIDTH: 213px">
						<asp:Label id="lblName" runat="server"></asp:Label></td>
				</tr>
				<tr>
					<td style="WIDTH: 93px">
						<asp:Label id="lblHeaderEmail" runat="server" Text="Email"></asp:Label></td>
					<td style="WIDTH: 213px; HEIGHT: 23px">
						<asp:Label id="lblEmail" runat="server"></asp:Label></td>
				</tr>
				<tr>
					<td style="WIDTH: 93px">
						<asp:Label id="lblHeaderCountryCode" runat="server" Text="CountryCode"></asp:Label></td>
					<td style="WIDTH: 213px; HEIGHT: 23px">
						<asp:Label id="lblCountryCode" runat="server"></asp:Label></td>
				</tr>
				<tr>
					<td style="WIDTH: 93px">
						<asp:Label id="lblHeaderBudget" runat="server" Text="Budget"></asp:Label></td>
					<td style="WIDTH: 213px; HEIGHT: 21px">
						<asp:Label id="lblBudget" runat="server"></asp:Label></td>
				</tr>
				<tr>
					<td style="WIDTH: 93px">
						<asp:Label id="lblHeaderUsed" runat="server" Text="Used"></asp:Label></td>
					<td style="WIDTH: 213px; HEIGHT: 21px">
						<asp:Label id="lblUsed" runat="server"></asp:Label></td>
				</tr>
			</table>
			<br>
			<asp:Label id="lblText" runat="server"></asp:Label>
	</form>
</body>
</html>