Issue with Comobox on DataGridView - sql

Question

I am using VB.NET to pull some data from an SQL database into a Datagridview.
I then want the user to be able to modify the information and save it back to the database, which I have working fine.
What I need to be able to do now is to restrict the values, but way of a combobox for the field Tarrif.
I have configured a DataSource called Tarrif1 and I am using the below code.
I have a couple of issues/questions.
Firstly the dropdown shows a single value of "System.Data.DataViewManagerListItemTypeDescriptor" not the Tarrif1 values.
Secondly, I now have 2 columns on my datatable called Tarrif, the original database one and the one I have added - How can I get the ComboBox to right back to the appropriate Tarrif database field.
Here is my code:
Imports System.Data.SqlClient
Imports System.Data.Common
Public Class ViewCustomersForm
Dim ds As DataSet = New DataSet()
Dim connStr As String = "server=barry-laptop\SQLEXPRESS; database=BillingReferenceData; integrated security=yes"
Dim sql As String = "SELECT * FROM Customers"
Dim conn As SqlConnection = New SqlConnection(connStr)
Dim comm As SqlCommand = New SqlCommand(Sql, conn)
Dim dataadapter As SqlDataAdapter = New SqlDataAdapter(comm)
Private Sub ViewCustomersForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'---open the connection and fill the dataset---
conn.Open()
dataadapter.Fill(ds, "Customers_table")
conn.Close()
DataGridView1.DataSource = ds
DataGridView1.DataMember = "Customers_table"
'---create a combobox column---
Dim comboBoxCol As New DataGridViewComboBoxColumn
'---set the header---
comboBoxCol.HeaderText = "Tarrifs"
'---data bind it---
comboBoxCol.DataSource = Tarrifs1
'comboBoxCol.DisplayMember = "Tarrif" // when I add these rows the new Tarrif column is not visible
'comboBoxCol.ValueMember = "Tarrif" // when I add these rows the new Tarrif column is not visible
'---add a combobox column to the DataGridView control---
DataGridView1.Columns.Add(comboBoxCol)
End Sub
Private Sub Button_Click_1(sender As Object, e As EventArgs) Handles Button1.Click
Dim sqlCmdBuilder As New SqlCommandBuilder(dataadapter)
sqlCmdBuilder.GetUpdateCommand()
dataadapter.Update(ds.Tables("Customers_table"))
End Sub
Private Sub DataGridView1_CellContentClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
End Sub
End Class
Hope that makes sense. Any help greatly appreciated.

Answer 1

A few things in this code:
dataadapter.Fill(ds, "Customers_table")
conn.Close()
DataGridView1.DataSource = ds
DataGridView1.DataMember = "Customers_table"
'---create a combobox column---
Dim comboBoxCol As New DataGridViewComboBoxColumn
'---set the header---
comboBoxCol.HeaderText = "Tarrifs"
'---data bind it---
comboBoxCol.DataSource = Tarrifs1
First, I'm not sure what happens whenever the code attempts to fill a DataSet that already has data in it. In my code, I never assume, so I always reinitialize it each time unless I need it:
ds = new DataSet()
Next, you are setting the DataSource for comboBoxCol as Tarrifs1, but I do not see that defined anywhere. You might want to look into that.
Finally, about the SQL: Dim sql As String = "SELECT * FROM Customers" I don't know what columns are in your Customers table. Is Tarrif an actual column?

Answer 2

I figured half my issue out.
I configured a second data connection to pull the Tarrif drop down from the Tarrifs table and display this as part of the customer data table.
My outstanding issues now, is that I need to write the select Tarrif value back to the Customers table.
All the other updated values save, just not sure how to write the Tarrif dropdown back to my SQL table
Here is my latest code.
Imports System.Data.SqlClient
Imports System.Data.Common
Public Class ViewCustomersForm
Dim ds As DataSet = New DataSet()
Dim connStr As String = "server=barry-laptop\SQLEXPRESS; database=BillingReferenceData; integrated security=yes"
Dim sql As String = "SELECT [Customer ID] ,[Customer Name] ,[Address] ,[City] ,[County] ,[Post Code] FROM [BillingReferenceData].[dbo].[Customers]"
Dim conn As SqlConnection = New SqlConnection(connStr)
Dim comm As SqlCommand = New SqlCommand(Sql, conn)
Dim dataadapter As SqlDataAdapter = New SqlDataAdapter(comm)
Dim con As New System.Data.SqlClient.SqlConnection("server=barry-laptop\SQLEXPRESS; database=Test; integrated security=yes")
Dim strSQL As String = "SELECT * FROM Tarrifs"
Dim da As New System.Data.SqlClient.SqlDataAdapter(strSQL, con)
Private Sub ViewCustomersForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'---open the connection and fill the dataset---
conn.Open()
dataadapter.Fill(ds, "Customers_table")
conn.Close()
DataGridView1.DataSource = ds
DataGridView1.DataMember = "Customers_table"
'---create a combobox column---
Dim comboBoxCol As New DataGridViewComboBoxColumn
'---set the header---
comboBoxCol.HeaderText = "Tarrifs"
'---data bind it---
da.Fill(ds, "Tarrifs")
comboBoxCol.DataSource = ds.Tables("Tarrifs")
comboBoxCol.DisplayMember = "Tarrif"
comboBoxCol.ValueMember = "Tarrif"
'---add a combobox column to the DataGridView control---
DataGridView1.Columns.Add(comboBoxCol)
End Sub
Private Sub Button_Click_1(sender As Object, e As EventArgs) Handles Button1.Click
Dim sqlCmdBuilder As New SqlCommandBuilder(dataadapter)
sqlCmdBuilder.GetUpdateCommand()
dataadapter.Update(ds.Tables("Customers_table"))
dataadapter.Update(ds.Tables("Tarrifs"))
End Sub
Private Sub DataGridView1_CellContentClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
End Sub
End Class