Form Load - Insert Or Update Data

I have a project in which i have a form in which there is add button to add pages. In form load the last entered page populates all the fields. Now thing is if user edits the values in controls it has to update the db with those fields and if the page doesn't exist in db it has to insert.

Here is my code
Private Sub inserting()
Dim cn As New OleDb.OleDbConnection
'Dim selectquery As String
cn.ConnectionString = ""
Dim cmd As New OleDb.OleDbCommand
[Code] .....

I initialized a global variable x and set its value to 0 in page load and in add button click to 1. Depending on x value it either inserts or updates the db in form closing and add button click. Now whats happening is If the user clicks on add button the page increments but if user doen;t enter any values and tries to close the empty form, value of x =1 and it tries to insert but as there are blank fields cmd.executenonquery throws an error.

"The field is too small to accept the amount of data you attempted to add. Try inserting or pasting less data."

What should I do so that it doesn't give an error. I am using access db.I even checked in db Except for primary key(pageno) all other fields have "allow zero length" as YES & "required" to NO.