Sending updates from datagridview to existing row in database - vb.net

Question

I am retrieving records from a database with the following code.
Dim SearchID As Integer = teacherID
Dim NewStudentID As Integer = studentID
Dim DisplayTable As New DataTable()
Dim da As New OleDbDataAdapter()
Dim sqlquery As String = ("select * from tblAppointments WHERE TeacherID =" & teacherID & "")
If conn.State = ConnectionState.Closed Then
conn.Open()
End If
Try
da.SelectCommand = New OleDbCommand(sqlquery, conn)
da.Fill(Finalds, "Display")
DisplayTable = Finalds.Tables("Display")
DisplayTable.Columns.Remove("Instrument")
DisplayTable.Columns.Remove("Room")
DisplayTable.Columns.Remove("TeacherID")
Registersgridview.DataSource = DisplayTable
Registersgridview.Columns(0).Visible = False
conn.Close()
Catch ex As Exception
MsgBox("There are no appointments in the database for " + Tutorcombox.Text)
End Try
It also there then added to a datagridview and certain columns are removed and some are hidden aswell.
Because its essentially a register, when the use clicks on the datagridview field that is a boolean it changes from false to true. I have been trying to send this back to the database, but have had no luck. I have tried the following :
Dim dt As DataTable = New DataTable("SendTable")
Dim row As DataRow
dt.Columns.Add("appID", Type.GetType("System.Int32"))
dt.Columns.Add("Present", Type.GetType("System.Boolean"))
For i = 0 To Registersgridview.Rows.Count - 1
row = dt.Rows.Add
row.Item("appID") = Registersgridview.Rows(i).Cells(0)
row.Item("Present") = Registersgridview.Rows(i).Cells(5)
Next
If conn.State = ConnectionState.Closed Then
conn.Open()
End If
Dim sqlquery As String = "Update tblAppointments SET Present = #Present WHERE appID = #appID"
Dim sqlcommand As New OleDbCommand
For Each newrow As DataRow In dt.Rows
With sqlcommand
.CommandText = sqlquery
.Parameters.AddWithValue("#Present", newrow.Item(1))
.Parameters.AddWithValue("#appID", newrow.Item(0))
.ExecuteNonQuery()
End With
conn.Close()
Next
But have had no luck with doing so, as it crashes without an error.
Can anyone help?

Answer 1

I solved the problem myself, if any of you are having similar problems here is the solution
Dim dt As DataTable = New DataTable("SendTable")
Dim row As DataRow
dt.Columns.Add("appID", Type.GetType("System.Int32"))
dt.Columns.Add("Present", Type.GetType("System.Boolean"))
For i = 0 To Registersgridview.Rows.Count - 1
Dim appID As Integer = Registersgridview.Rows(i).Cells(0).Value
Dim present As Boolean = Registersgridview.Rows(i).Cells(4).Value
row = dt.Rows.Add
row.Item("appID") = appID
row.Item("Present") = present
Next
If conn.State = ConnectionState.Closed Then
conn.Open()
End If
Dim sqlquery As String = "UPDATE tblAppointments SET Present = #Present WHERE appID = #appID"
Dim sqlcommand As New OleDbCommand
For Each newrow As DataRow In dt.Rows
With sqlcommand
.CommandText = sqlquery
.Parameters.AddWithValue("#Present", newrow.Item(1))
.Parameters.AddWithValue("#appID", newrow.Item(0))
.Connection = conn
.ExecuteNonQuery()
End With
Next
conn.Close()
Registersgridview.DataSource = Nothing
dt.Clear()

Answer 2

try this:
Dim dt As DataTable = New DataTable("SendTable")
Dim row As DataRow
dt.Columns.Add("appID", Type.GetType("System.Int32"))
dt.Columns.Add("Present", Type.GetType("System.Boolean"))
For i = 0 To Registersgridview.Rows.Count - 1
row = dt.Rows.Add
row.Item("appID") = Registersgridview.Rows(i).Cells(0)
row.Item("Present") = Registersgridview.Rows(i).Cells(5)
Next
If conn.State = ConnectionState.Closed Then
conn.Open()
End If
Dim sqlquery As String = "Update tblAppointments SET Present = #Present WHERE appID = #appID"
Dim sqlcommand As New OleDbCommand
For Each newrow As DataRow In dt.Rows
With sqlcommand
.CommandText = sqlquery
.Parameters.AddWithValue("#Present", newrow.Item(5))
.Parameters.AddWithValue("#appID", newrow.Item(0))
.ExecuteNonQuery()
End With
conn.Close()
Next