IDataAdapter and basic commands (insert, update, delete)

Question

I have a function to bind data from a SQL database to a gridview. So far it worked well using this:

    Dim dad As SqlDataAdapter
    Dim bs As BindingSource
    Dim dtb As DataTable
    Private Sub getDataSQL(ByVal selectCommand As String, ByVal connectionString As String)
        dtb = New DataTable
        Dim cnn As New SqlConnection(connectionString)
        cnn.Open()
        dad = New SqlDataAdapter(selectCommand, cnn)
        Dim basiccommands = New SqlCommandBuilder(dad)
        dad.InsertCommand = basiccommands.GetInsertCommand
        dad.UpdateCommand = basiccommands.GetUpdateCommand
        dad.DeleteCommand = basiccommands.GetDeleteCommand
        dad.Fill(dtb)
        bs = New BindingSource
        bs.DataSource = dtb
        navigator_main.BindingSource = bs 'this is a binding navigator
        dgv_main.DataSource = bs 'this is the main datagridview
        cnn.Close()
    End Sub

When the user adds/edits/deletes a row I call:

bs.EndEdit()
dad.Update(dtb)

Now I must reuse the getData function to populate the gridview by connecting to different types of databases (mainly MySQL, ODB, SQL). For that I created an interface that allows reusing a lot of functions by indicating the type of connection:

Public Interface IDataBaseHelper
    Function openConnection(ByVal conn_string As String) As Boolean
    Function executeQuery(ByVal query As String) As IDataReader
    Function executeQuery(ByVal command As IDbCommand) As IDataReader
    Function executeNonQuery(ByVal query As String) As Integer
    Function createSQLCommand(ByVal query As String) As IDbCommand
    Function getDataAdapter(ByVal query As String) As IDataAdapter
    Sub closeConnection()
End Interface

The new function looks like this:

    Private mBindingSource As New BindingSource()
    Private mDataAdapter As IDataAdapter
    Private mDataSet As DataSet
    Private Sub getData(ByVal selectCommand As String, ByVal connectionString As String, ByVal connectionType As String)
        'Connection types are defined in FDataBaseHelper: FDataBaseHelper.SQLSERVER_ .MYSQL_ .ODBC_
        Dim cnn = FDataBaseHelper.createInstance(connectionType)
        cnn.openConnection(connectionString)
        mDataAdapter = cnn.getDataAdapter(selectCommand)
        mDataSet = New DataSet()
        Dim dtb As New DataTable
        mDataAdapter.Fill(mDataSet)
        dtb = mDataSet.Tables(0)
        mBindingSource.DataSource = dtb
        navigator_main.BindingSource = mBindingSource
        dgv_main.DataSource = mBindingSource
    End Sub

where the clase FDataBaseHelper looks like:

Public Class FDataBaseHelper
    'Class factory depending on type of connection
    Public Const SQLSERVER_ = "SQLServer"
    Public Const MYSQL_ = "MySQL"
    Public Const ODBC_ = "ODBC"

    Public Shared Function createInstance(conn_type As String) As IDataBaseHelper
        If conn_type = SQLSERVER_ Then
            Return New DataBaseHelperSQL
        ElseIf conn_type = MYSQL_ Then
            Return New DataBaseHelperMySQL
        ElseIf conn_type = ODBC_ Then
            Return New DataBaseHelperODBC
        End If
        Return Nothing
    End Function

End Class

And the getDataAdapter function (e.g. for the DataBaseHelperSQL) is:

Public Function getDataAdapter(query As String) As IDataAdapter Implements IDataBaseHelper.getDataAdapter
        Dim command = createSQLCommand(query)
        Dim adapter = New SqlDataAdapter(command)
        Return adapter
    End Function

The datagridview gets populated nicely, but any changes made by the user are not stored in the database. The problem is that IDataAdapter does not have InsertCommand, UpdateCommand and DeleteCommand as members, and I'm getting an error in:

mAdapter.Update(mDataSet)

The error says: "Update requires a valid InsertCommand when passed DataRow collection with new rows" I have tried several suggested solutions but to no avail, since I've not found anyone doing it using an interface. Any help would be greatly appreciated

EDIT: finally the solution was as easy as moving the definition of the basic commands inside the helper classes. E.g. for the DataBaseHelperSQL the getDataAdapter method stands:

Public Function getDataAdapter(query As String) As IDataAdapter Implements IDataBaseHelper.getDataAdapter
        Dim command = createSQLCommand(query)
        Dim adapter = New SqlDataAdapter(command)
        Dim basiccommands = New SqlCommandBuilder(adapter)
        adapter.InsertCommand = basiccommands.GetInsertCommand
        adapter.UpdateCommand = basiccommands.GetUpdateCommand
        adapter.DeleteCommand = basiccommands.GetDeleteCommand
            Return adapter
End Function

Answer 1

Finally the solution was as easy as moving the definition of the basic commands inside the helper classes. E.g. for the DataBaseHelperSQL the getDataAdapter method stands:

Public Function getDataAdapter(query As String) As IDataAdapter Implements IDataBaseHelper.getDataAdapter
        Dim command = createSQLCommand(query)
        Dim adapter = New SqlDataAdapter(command)
        Dim basiccommands = New SqlCommandBuilder(adapter)
        adapter.InsertCommand = basiccommands.GetInsertCommand
        adapter.UpdateCommand = basiccommands.GetUpdateCommand
        adapter.DeleteCommand = basiccommands.GetDeleteCommand
            Return adapter
End Function