How to add dates every 3 months for a year VB.NET

See more:

VB

Hello Everyone,

I have a code which I insert values every month in vb.net, what I need now is to insert certain values every 3 months. I have a textBox which I can decide how many times or how many months I want to insert into the database.
This is the code that I insert every month how many times I want :

Dim startdate As DateTime = DateTimePickerFixCosts1.Value
           Dim enddate As DateTime = startdate.AddMonths(Convert.ToInt32(txtNumberofMonths.Text))
           Dim amount As Decimal = Decimal.Parse(txtPriceFixCosts.Text)
           Const query As String = "INSERT INTO Test_Table(Date,Description,Payment,Quantity,Price,Department,Status,Store) VALUES (@date,@description,@payment,@quantity,@price,@department,@status,@Store)"
           Do While (startdate > enddate)

               Using conn As SqlConnection = New SqlConnection("Data Source=#######\SQLEXPRESS;Initial Catalog=Expenses;Trusted_Connection=yes;")
                   Using command As SqlCommand = New SqlCommand(query, conn)

                       command.Parameters.AddWithValue("@description", TxtItemDescFixCosts.Text)
                       command.Parameters.AddWithValue("@payment", TxtPaymentFixCosts.Text)
                       command.Parameters.AddWithValue("@price", amount)
                       command.Parameters.AddWithValue("@date", startdate)
                       command.Parameters.AddWithValue("@status", ComboBox1.Text)
                       command.Parameters.AddWithValue("@quantity", TextBoxIDd.Text)
                       command.Parameters.AddWithValue("@department", TxtFixCosts.Text)
                       command.Parameters.AddWithValue("@Store", TxtStore.Text)

                       conn.Open()
                       command.ExecuteNonQuery() ' NB: Don't use ExecuteReader when the query doesn't return anything!
                       startdate = startdate.AddMonths(1)
                   End Using

               End Using
           Loop
           MsgBox("Your Data has been Inserted")

What I have tried:

I tried to change the add months to a

different number but it won't record anything.

If CategoryBox.SelectedItem = "Monthly" Then
        Dim startdate As DateTime = DateTimePickerFixCosts1.Value
        Dim enddate As DateTime = startdate.AddMonths(Convert.ToInt32(txtNumberofMonths.Text))
        Dim amount As Decimal = Decimal.Parse(txtPriceFixCosts.Text)
        Const query As String = "INSERT INTO Test_Table(Date,Description,Payment,Quantity,Price,Department,Status,Store) VALUES (@date,@description,@payment,@quantity,@price,@department,@status,@Store)"
        Do While (startdate > enddate)

            Using conn As SqlConnection = New SqlConnection("Data Source=#######\SQLEXPRESS;Initial Catalog=Expenses;Trusted_Connection=yes;")
                Using command As SqlCommand = New SqlCommand(query, conn)

                    command.Parameters.AddWithValue("@description", TxtItemDescFixCosts.Text)
                    command.Parameters.AddWithValue("@payment", TxtPaymentFixCosts.Text)
                    command.Parameters.AddWithValue("@price", amount)
                    command.Parameters.AddWithValue("@date", startdate)
                    command.Parameters.AddWithValue("@status", ComboBox1.Text)
                    command.Parameters.AddWithValue("@quantity", TextBoxIDd.Text)
                    command.Parameters.AddWithValue("@department", TxtFixCosts.Text)
                    command.Parameters.AddWithValue("@Store", TxtStore.Text)

                    conn.Open()
                    command.ExecuteNonQuery() ' NB: Don't use ExecuteReader when the query doesn't return anything!
                    startdate = startdate.AddMonths(3)
                End Using

            End Using
        Loop
        MsgBox("Your Data has been Inserted")


    End If

So I need to insert this certain information every 3 months for a certain period of time but it doesn't work like this.

Any help is much appreciated.

Thankfully