Edit Gridview columns to MySQL - mysql

Question

When I try my code to update the GridViewBox to update to my database I get the following error message
Object Reference not set to an instance of an Object
But I cannot quite figure it out. Would appreciate any Help I can get.
Imports MySql.Data.MySqlClient
Public Class Form1
//GLOBAL DELARATION
Dim conString As String = "Server=xxx;" & "Database=xxx;" & "Uid=xxx;" & "xxx;"
Dim con As New MySqlConnection(conString)
Dim cmd As MySqlCommand
Dim adapter As MySqlDataAdapter
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
//TODO: This line of code loads data into the 'OlejnaDataSet.people' table. You can move, or remove it, as needed.
Me.PeopleTableAdapter.Fill(Me.OlejnaDataSet.people)
DataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect
End Sub
Private Sub hent()
Me.PeopleTableAdapter.Fill(Me.OlejnaDataSet.people)
End Sub
Private Sub cleartxt()
TextBox_name.Text = ""
TextBox_position.Text = ""
TextBox_team.Text = ""
End Sub
Private Sub Add()
Dim sql As String = "INSERT INTO people(Name,Position,Team) VALUES(#NAME,#POSITION,#TEAM)"
cmd = New MySqlCommand(sql, con)
//PARAMETERS
cmd.Parameters.AddWithValue("#NAME", TextBox_name.Text)
cmd.Parameters.AddWithValue("#POSITION", TextBox_position.Text)
cmd.Parameters.AddWithValue("#TEAM", TextBox_team.Text)
//Open Connection and INSERT
Try
con.Open()
If cmd.ExecuteNonQuery() > 0 Then
MsgBox("Added")
cleartxt()
End If
con.Close()
hent()
Catch ex As Exception
MsgBox(ex.Message)
con.Close()
End Try
End Sub
//UPDATE DATABASE
Private Sub UpdateDG(id As String)
Dim sql As String = "UPDATE people SET name='" + TextBox_name.Text + "', position='" + TextBox_position.Text + "', team='" + TextBox_team.Text + "' WHERE ID='" + id + "'"
//Open CON, EXECUTE UPDATE, CLOSE
Try
con.Open()
adapter.UpdateCommand = con.CreateCommand()
adapter.UpdateCommand.CommandText = sql
If adapter.UpdateCommand.ExecuteNonQuery() > 0 Then
MsgBox("You have now updated")
cleartxt()
End If
con.Close()
//REFRESH
hent()
Catch ex As Exception
MsgBox(ex.Message)
con.Close()
End Try
End Sub
Private Sub ButtonAdd_Click(sender As Object, e As EventArgs) Handles ButtonAdd.Click
Add()
End Sub
Private Sub ButtonDelete_Click(sender As Object, e As EventArgs) Handles ButtonDelete.Click
End Sub
Private Sub ButtonUpdate_Click(sender As Object, e As EventArgs) Handles ButtonUpdate.Click
Dim id As String = DataGridView1.SelectedRows(0).Cells(0).Value
UpdateDG(id)
End Sub
Private Sub DataGridView1_MouseClick(sender As Object, e As MouseEventArgs) Handles DataGridView1.MouseClick
Dim name As String = DataGridView1.SelectedRows(0).Cells(1).Value
Dim position As String = DataGridView1.SelectedRows(0).Cells(2).Value
Dim team As String = DataGridView1.SelectedRows(0).Cells(3).Value
TextBox_name.Text = name
TextBox_position.Text = position
TextBox_team.Text = team
End Sub
End Class

Answer 1

Hope you have clicked Update button without select any rows in your DataGrid
Change your Update Button Click Event as follows:
Private Sub ButtonUpdate_Click(sender As Object, e As EventArgs) Handles ButtonUpdate.Click
If DataGridView1.SelectedRows.Count > 0 Then
Dim id As String = DataGridView1.SelectedRows(0).Cells(0).Value
UpdateDG(id)
End If
End Sub
Update
Please Declare and Intialize your Sql Adapter
Use as below:
SqlDataAdapter adapter = new SqlDataAdapter();
//UPDATE DATABASE
Private Sub UpdateDG(id As String)
Dim sql As String = "UPDATE people SET name='" + TextBox_name.Text + "', position='" + TextBox_position.Text + "', team='" + TextBox_team.Text + "' WHERE ID='" + id + "'"
//Open CON, EXECUTE UPDATE, CLOSE
Try
SqlDataAdapter adapter = new SqlDataAdapter();
con.Open()
adapter.UpdateCommand = con.CreateCommand()
adapter.UpdateCommand.CommandText = sql
If adapter.UpdateCommand.ExecuteNonQuery() > 0 Then
MsgBox("You have now updated")
cleartxt()
End If
con.Close()
//REFRESH
hent()
Catch ex As Exception
MsgBox(ex.Message)
con.Close()
End Try
End Sub