Index out of range exception cannot find column - vb.net

Question

Hello I have this problem in came upon when trying to do simple manual search in vb.net. It says System.IndexOutOfRangeException: 'Cannot find column 4.'
could anyone explain what this means i am quite new to coding and dont quite get what i could to do fix this. In the attached database i have only one table called customer with 4 columns custid, custfname, custlname and dob.
This is the code and the error occurs in the btnNext and Navigaterecords. The database was made in sqlite
Imports System.Data.SQLite
Public Class Form1
Dim inc As Integer
Dim MaxRows As Integer
Dim ConnectionString As String = "Data Source=dbRoomBookings.db"
Dim ds As New DataSet
Dim dt As New DataTable
Dim mSQL As String = "SELECT * FROM Customer"
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim con As New SQLiteConnection(ConnectionString)
Dim cmd As New SQLiteCommand(mSQL, con)
con.Open()
Dim da As New SQLiteDataAdapter(cmd)
da.Fill(ds, "customer")
dt = ds.Tables(0)
MaxRows = ds.Tables("customer").Rows.Count
con.Close()
Dim msSQL As String = "SELECT * FROM customer;"
dgvSearchResults.DataSource = display(msSQL, "customer")
End Sub
Private Sub BtnNext_Click(sender As Object, e As EventArgs) Handles btnNext.Click
If inc <> MaxRows - 1 Then
inc = inc + 1
txtCusId.Text = ds.Tables("customer").Rows(inc).Item(0)
txtFname.Text = ds.Tables("customer").Rows(inc).Item(1)
txtLname.Text = ds.Tables("customer").Rows(inc).Item(2)
cboDay.Text = ds.Tables("customer").Rows(inc).Item(3)
cboMonth.Text = ds.Tables("customer").Rows(inc).Item(4)
cboYear.Text = ds.Tables("Customer").Rows(inc).Item(5)
Else
MsgBox("no more rows")
End If
End Sub
Sub navigaterecords()
txtCusId.Text = ds.Tables("customer").Rows(inc).Item(0)
txtFname.Text = ds.Tables("customer").Rows(inc).Item(1)
txtLname.Text = ds.Tables("customer").Rows(inc).Item(2)
cboDay.Text = ds.Tables("customer").Rows(inc).Item(3)
cboMonth.Text = ds.Tables("customer").Rows(inc).Item(4)
cboYear.Text = ds.Tables("customer").Rows(inc).Item(5)
txtDbo.Text = ds.Tables("customer").Rows(inc).Item(3) & "/" & ds.Tables("customer").Rows(inc).Item(4) & "/" & ds.Tables("customer").Rows(inc).Item(5)
End Sub
Private Sub BtnPrevious_Click(sender As Object, e As EventArgs) Handles btnPrevious.Click
If inc > 0 Then
inc = inc - 1
navigaterecords()
Else
MsgBox("no more rows")
End If
End Sub
Private Sub BtnFirst_Click(sender As Object, e As EventArgs) Handles btnFirst.Click
If inc <> 0 Then
inc = 0
navigaterecords()
End If
End Sub
Private Sub BtnLast_Click(sender As Object, e As EventArgs) Handles btnLast.Click
If inc <> MaxRows - 1 Then
inc = MaxRows - 1
navigaterecords()
Else
End If
End Sub
Private Sub BtnSearch_Click(sender As Object, e As EventArgs) Handles btnSearch.Click
Dim sSQL As String
Dim newds As New DataSet
Dim newdt As New DataTable
If txtSearchFname.Text <> "" Then
sSQL = "SELECT * FROM customer WHERE custfname LIKE'" & txtSearchFname.Text & "%'"
Dim con As New SQLiteConnection(ConnectionString)
Dim cmd As New SQLiteCommand(sSQL, con)
con.Open()
Dim da As New SQLiteDataAdapter(cmd)
da.Fill(newds, "customer")
newdt = newds.Tables(0)
dgvSearchResults.DataSource = newdt
con.Close()
ElseIf txtSearchId.Text <> "" Then
sSQL = "SELECT * FROM customer WHERE custid ='" & txtSearchId.Text & "'"
Dim con As New SQLiteConnection(ConnectionString)
Dim cmd As New SQLiteCommand(sSQL, con)
con.Open()
Dim da As New SQLiteDataAdapter(cmd)
da.Fill(newds, "customer")
newdt = newds.Tables(0)
dgvSearchResults.DataSource = newdt
con.Close()
End If
End Sub
Private Sub BtnDelete_Click(sender As Object, e As EventArgs) Handles btnDelete.Click
Dim con2 As New SQLiteConnection
Dim da2 As New SQLiteDataAdapter
Dim dsql, qsql As String
Dim ds2 As New DataSet
Dim dt2 As DataTable
con2 = New SQLiteConnection(ConnectionString)
dsql = "DELETE FROM customer WHERE custid = " & txtSearchId.Text & ""
qsql = "SELECT * FROM customer"
Dim cmd As New SQLiteCommand(qsql, con2)
con2.Open()
da2.DeleteCommand = con2.CreateCommand
da2.DeleteCommand.CommandText = dsql
da2.DeleteCommand.ExecuteNonQuery()
MsgBox("Row(s) Deleted !! ")
Dim da3 As New SQLiteDataAdapter(cmd)
da3.Fill(ds2, "customer")
dt2 = ds2.Tables(0)
dgvSearchResults.DataSource = dt2
con2.Close()
End Sub
Private Sub BtnUpdate_Click(sender As Object, e As EventArgs) Handles btnUpdate.Click
Dim con3 As New SQLiteConnection
Dim da3 As New SQLiteDataAdapter
con3 = New SQLiteConnection(ConnectionString)
Dim usql As String = "UPDATE Customer SET custfname = '" & txtFname.Text & "'" & "WHERE custid =" & CInt(txtCusId.Text) & ""
con3.Open()
da3.UpdateCommand = con3.CreateCommand
da3.UpdateCommand.CommandText = usql
da3.UpdateCommand.ExecuteNonQuery()
MsgBox("Row Updated")
End Sub
Private Sub BtnAdd_Click(sender As Object, e As EventArgs) Handles btnAdd.Click
Dim isql As String = "INSERT INTO customer(custfname, custlname, dob) VALUES('" _
& txtFname.Text & "','" & txtLname.Text & "','" & cboYear.Text _
& "-" & cboMonth.Text & "-" & cboDay.Text & "');"
Dim msql As String = "SELECT * FROM customer"
add(isql)
'refresh the Data Grid
dgvSearchResults.DataSource = display(msql, "customer")
End Sub
End Class

Answer 1

Here is the specific documentation on IndexOutOfRangeException: https://learn.microsoft.com/en-us/dotnet/api/system.indexoutofrangeexception
For visibility, the definition is:
The exception that is thrown when an attempt is made to access an
element of an array or collection with an index that is outside its
bounds.
In your case, you are trying to get a value by passing the index of a column but the index you're passing is greater than the total number of columns.
Assuming that your table definition has the following columns: custfname, custlname, and dob, the following represents when the Exception would occur:
Get column 0, returns the value of custfname
Get column 1, returns the value of custlname
Get column 2, returns the value of dob
Get column 3, throws an IndexOutOfRangeException
The same thing would also happen if you tried to get a value at a negative index too.

Answer 2

You have a 4-column table which will have indexes from 0 to 3 only:
custid is column 0, custfname is column 1, custfname is column 2, and dob is column 3.
So any attempt to access ds.Tables("customer").Rows(inc).Item(4) (and (5), etc) will yield an Index out of range exception.
But you seem to know that the table only has 4 columns; why are you then attempting to access columns that you know don't exist? I'm a bit confused by that. If you're trying to split DOB into day/month/year, you'll have to manipulate the dob value from the DOB composite column, Item(3).