Using Methods with Object Oriented Database Development with VB.NET 2005 - Dealing with method overloading to attain more flexibility

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Let us work with the method "add" now. It is defined as follows:

    Public Sub add()
        Dim cn As New SqlConnection("Data Source=.sql2k5;initial
catalog=sample;user id=sa;password=eXpress2005")
        Dim cmd As New SqlCommand
        Try
            With cmd
                .CommandText = "insert into sample.dbo.emp values ('" &
m_empno & "','" & m_ename & "," & m_sal & "," & m_deptno & ")"
                .Connection = cn
                .Connection.Open()
                .ExecuteNonQuery()
            End With
        Catch ex As Exception
            Throw New Exception(ex.Message)
        Finally
            If cmd.Connection.State = ConnectionState.Open Then
                cmd.Connection.Close()
            End If
            cmd.Dispose()
            cn.Dispose()
        End Try
    End Sub

The following is the code needed to execute the above method:

    Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles btnAdd.Click

        Me.lblErrMsg.Text = ""
        Try
            Dim ep As New Emp
            With ep
                .m_empno = Me.txtEmpno.Text
                .m_deptno = Me.txtDeptno.Text
                .m_ename = Me.txtEname.Text
                .m_sal = Me.txtSal.Text
                .add()
            End With
        Catch ex As Exception
            Me.lblErrMsg.Text = ex.Message
        End Try
    End Sub

From the above code, you can observe that I am assigning all the values to the fields and then only calling the method "add." But, let us consider that I would like to have one more method with the name "add" (for flexibility) which accepts all the fields as parameters.  The following would be another method named "add" (apart from the old method "add").

PublicSub add(ByVal empno As String, ByVal ename As String, ByVal sal As
Double, ByVal deptno As Integer)
        m_empno = empno
        m_ename = ename
        m_sal = sal
        m_deptno = deptno
        add()
    End Sub

The following would be the code needed to execute the above method:

PrivateSub btnAdd_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles btnAdd.Click
        Me.lblErrMsg.Text = ""
        Try
            Dim ep As New Emp
            ep.add(Me.txtEmpno.Text, Me.txtEname.Text, Me.txtSal.Text,
Me.txtDeptno.Text)
        Catch ex As Exception
            Me.lblErrMsg.Text = ex.Message
        End Try
    End Sub

Now, you can observe that I defined two methods with the same name ("add"), but with a difference in parameters.  You can call the two methods individually at any time. Depending on the parameters, it would automatically identify the method to execute. This is called "method overloading."

Next: Developing methods with parameters as objects >>
 

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