Updating Datagridview? - vb.net

Question

I'm trying to figure out how to update a selected row in my DataGridView. I would like my system to recognize an existing row of information I've selected from my datagridview (I've set it to full row select btw) and update/edit the information by changing them with the textboxes and comboboxes I used to add them. Everything in my table is set as Text datatype, besides ID which is auto number. However, I get an error with the code I used below. Any help will be greatly appreciated! Thank you :) (I'm gonna provide a link to the screenshot of the error since I don't have enough reputation.)
* New error when I enclose Section with brackets
http://i.imgur.com/gs8rVhB.png
Imports System.Data.OleDb
Public Class AdmMain
Dim con As New OleDbConnection
Sub fillcombo()
strsql = " select yrgr from yearandgrade"
Dim acscmd As New OleDb.OleDbCommand
acscmd.CommandText = strsql
acscmd.Connection = acsconn
acsdr = acscmd.ExecuteReader
While (acsdr.Read())
cboyr.Items.Add(acsdr("yrgr"))
End While
acscmd.Dispose()
acsdr.Close()
End Sub
Sub comb2()
strsql = " select sections from sectio"
Dim acscmd As New OleDb.OleDbCommand
acscmd.CommandText = strsql
acscmd.Connection = acsconn
acsdr = acscmd.ExecuteReader
While (acsdr.Read())
cbosec.Items.Add(acsdr("sections"))
End While
acscmd.Dispose()
acsdr.Close()
End Sub
Private Sub LinkLabel1_LinkClicked(sender As System.Object, e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles LinkLabel1.LinkClicked
If MessageBox.Show("Are you sure you want to logout?", "Logout", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = Windows.Forms.DialogResult.Yes Then
MessageBox.Show("You have successfully logged out of VCM's Library Information System!", "Logout Confirmed")
Me.Close()
LoginUser.Show()
End If
End Sub
Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
Me.TxtID.Text = ""
Me.txtFName.Text = ""
Me.txtMName.Text = ""
Me.txtLName.Text = ""
Me.cboyr.Text = ""
Me.cbosec.Text = ""
Me.TxtID.Focus()
End Sub
Private Sub AdmMain_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
Module1.connect()
Me.fillcombo()
Me.comb2()
con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=C:\Thesis\Thesis\Database1.accdb"
con.Open()
datagridshow()
End Sub
Private Sub datagridshow()
Dim ds As New DataSet
Dim dt As New DataTable
ds.Tables.Add(dt)
Dim da As New OleDbDataAdapter
da = New OleDbDataAdapter("select * from students ", con)
da.Fill(dt)
DataGridView1.DataSource = dt.DefaultView
con.Close()
End Sub
Private Sub btnAdd_Click(sender As System.Object, e As System.EventArgs) Handles btnAdd.Click
Dim rbdtext As String = cboyr.SelectedItem.ToString
Dim uno As String = cbosec.SelectedItem.ToString
Try
Dim cnString = "Provider=Microsoft.ACE.OLEDB.12.0;" & _
"Data Source=C:\Thesis\Thesis\Database1.accdb"
Dim sqlquery As String = "INSERT INTO students " & _
"(StudentID, FirstName,MiddleName,LastName,Yr, [Section]) " & _
"VALUES (#studid, #fname,#mname,#lname,#yr, #sec)"
' Use this form to initialize both connection and command to
' avoid forgetting to set the appropriate properties....
Using conn = New System.Data.OleDb.OleDbConnection(cnString)
Using cmd = New System.Data.OleDb.OleDbCommand(sqlquery, conn)
conn.Open()
cmd.Parameters.AddWithValue("#studid", TxtID.Text)
cmd.Parameters.AddWithValue("#fname", txtFName.Text)
cmd.Parameters.AddWithValue("#mname", txtMName.Text)
cmd.Parameters.AddWithValue("#lname", txtLName.Text)
cmd.Parameters.AddWithValue("#yr", rbdtext)
cmd.Parameters.AddWithValue("#sec", uno)
If TxtID.Text = "" Or txtFName.Text = "" Or txtMName.Text = "" Or txtLName.Text = "" Or cboyr.SelectedIndex = -1 Or cbosec.SelectedIndex = -1 Then
MessageBox.Show("Please complete the required fields.", "Admin", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Return
Else
Dim rowsInserted = cmd.ExecuteNonQuery()
If rowsInserted > 0 Then
MessageBox.Show("One record successfully added!", "Added!")
datagridshow()
Else
MessageBox.Show("Failure to add new record!", "Failure!")
End If
End If
End Using
End Using
Catch ex As Exception
MsgBox(ex.ToString)
End Try
End Sub
Private Sub TxtID_KeyPress(sender As Object, e As System.Windows.Forms.KeyPressEventArgs) Handles TxtID.KeyPress
'97 - 122 = Ascii codes for simple letters
'65 - 90 = Ascii codes for capital letters
'48 - 57 = Ascii codes for numbers
If Asc(e.KeyChar) <> 8 Then
If Asc(e.KeyChar) < 48 Or Asc(e.KeyChar) > 57 Then
e.Handled = True
End If
End If
End Sub
Private Sub btnEdit_Click(sender As System.Object, e As System.EventArgs) Handles btnEdit.Click
Dim rbdtext As String = cboyr.SelectedItem.ToString
Dim uno As String = cbosec.SelectedItem.ToString
Try
Dim cnString = "Provider=Microsoft.ACE.OLEDB.12.0;" & _
"Data Source=C:\Thesis\Thesis\Database1.accdb"
Dim sqlquery As String = "UPDATE Students SET StudentID = #STUDID, FirstName = #FNAME, MiddleName = #MNAME, LastName= #LNAME, Yr = #YRR, [Section] = #SEC WHERE StudentID = #STUDID, FirstName =#FNAME, MiddleName = #MNAME, LastName= #LNAME, Yr = #YRR, [Section] = #SEC"
' Use this form to initialize both connection and command to
' avoid forgetting to set the appropriate properties....
Using conn = New System.Data.OleDb.OleDbConnection(cnString)
Using cmd = New System.Data.OleDb.OleDbCommand(sqlquery, conn)
conn.Open()
cmd.Parameters.AddWithValue("#STUDID", TxtID.Text)
cmd.Parameters.AddWithValue("#FNAME", txtFName.Text)
cmd.Parameters.AddWithValue("#MNAME", txtMName.Text)
cmd.Parameters.AddWithValue("#LNAME", txtLName.Text)
cmd.Parameters.AddWithValue("#YRR", rbdtext)
cmd.Parameters.AddWithValue("#SEC", uno)
If TxtID.Text = "" Or txtFName.Text = "" Or txtMName.Text = "" Or txtLName.Text = "" Or cboyr.SelectedIndex = -1 Or cbosec.SelectedIndex = -1 Then
MessageBox.Show("Please complete the required fields.", "Admin", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Return
Else
Dim rowsInserted = cmd.ExecuteNonQuery()
If rowsInserted > 0 Then
MessageBox.Show("One record successfully updated!", "Updated!")
datagridshow()
Else
MessageBox.Show("Failure to update new record!", "Failure!")
End If
End If
End Using
End Using
Catch ex As Exception
MsgBox(ex.ToString)
End Try
End Sub
End Class

Answer 1

The syntax of a UPDATE...WHERE expression requires a condition that uniquely identifies the record to UPDATE. If the condition is an expression composed of more than one field/value then these conditions should be combined using AND or OR operators not using commas.
Usually the condition in the WHERE clause identifies the record to be updated using the PRIMARY KEY of the table (in your case this seems to be the StudentID field) so you just need to write
Dim sqlquery As String = "UPDATE Students SET FirstName = #FNAME, " &_
"MiddleName = #MNAME, LastName= #LNAME, Yr = #YRR, " & _
"[Section] = #SEC " & _
"WHERE StudentID = #STUDID"
Note that if StudentID is the PRIMARYKEY you don't try to change/update it bacause this could cause inconsistencies in your other database tables that refer (have a relationship) with the Students table
Finally, the OleDb provider don't recognize the parameter by their name, the provider expects that each parameter passed is in the same order in which the parameter placeholders appears in the command text (It use the position of the parameter to pass the value to the database engine), so you need to change also the order in which you set up the parameter collection for the UPDATE
cmd.Parameters.AddWithValue("#FNAME", txtFName.Text)
cmd.Parameters.AddWithValue("#MNAME", txtMName.Text)
cmd.Parameters.AddWithValue("#LNAME", txtLName.Text)
cmd.Parameters.AddWithValue("#YRR", rbdtext)
cmd.Parameters.AddWithValue("#SEC", uno)
cmd.Parameters.AddWithValue("#STUDID", TxtID.Text)