Sorry for the last post, It was completly wrong.

Hope this time I can explain better.

I want to fill a Combo according the value of another Combo.

I have this scenario

Table States

IdState - Int32

Statename - String

Table Cities

IdCity - Int32

IdState - Int32

CityName - String

Table Streets

IdStreets - Int32

IdCity - Int32

IdState - Int32

StreetName - String

The three tables have relations defined.

I create a form to mantein the states, the a form to mantein the cities and all fine.

I create a new form to mantein the streets, and here is my problem. In this user first select the state from a combo and the according to the selected state a second combo must be filled with only the cities of the state selected in the first combo.

There are three BO, one for the form, another for the States and a thierd one for the cities.

In the BO of the cities I have this:

Public Sub FillByState(ByVal State As Integer)...

loCommand.CommandText = "SELECT * FROM Cities WHERE IdState = @IdSate"

...

End Sub

The fill is copy of the one used in the tutorial. The PopulationDataSourceSettings for the CitiesBO are set to execute the FillByState: CitiesBO.FillByState(System.Int32) and PopulateOnFormLoad is FormLoad

In the combo of State I add this code for the SelectedvalueChanged event

Me.CitiesBO.FillBySate(Me.ComboBoxState.SelectedValue)

Me.ComboBoxCities.Requery()

But when I select a state the combo for the cities is not filled.

What do I need to do?

Regards

Please post the code of the populating event and the one that is causing the error.  It is a bit difficult to help you debug without looking at your code.  I am sure it is something very simple.  Also FYI, what you are trying to do with all your combos, can also be done in the Dialog Browser, in case you needed to know.

This is what I have:

I uses a Contry - States - Cites sample, my tables are Sitios (sites), Categorias (categories) and Subcategorías (subcategories), is the same.

When the user add a new record or edit one existing, firs select the site, the category and the subcategory, then two more fields that are just text.

I already made a for for add sites, then another for add categories, in that I used the code you kindly provide me, and works fine.

In this form is for subcategories, I repeat all code just adjusting the for the last combo.

In the Sites combo the PopulatingDataSourceSettings is: CategoriasPubBO.FillBySitio(System.Int32) FillBySitio is a query to the BO that retrieves all the values in the table. The PopuleteOnFormLoad is on FormLoad

In the event SelectedIndexChanged has this: Me.cboCategoria.Requery()

The Cataegories Combo PopulatingDataSourceSettings is: CategoriasPubBO.FillBySitio(System.Int32) where the query in the BO is:

Public Sub FillBySitio(ByVal Sitio As Integer)

'-- Locals

Dim loCommand As New SqlCommand()

'-- Build the query

loCommand.CommandText = "SELECT * FROM Categorias_Pub WHERE IdSitio = @IdSitio"

'-- Add parameter

loCommand.Parameters.Add("@IdSitio", SqlDbType.Int)

loCommand.Parameters("@IdSitio").Value = Sitio

'-- Execute command

Me.FillDataTable(loCommand)

End Sub

In the SelectedIndexChanged has this:

If Me.DetalleSubcategoriasBO.Count > 0 Then

e.Parameters(0).Value = Me.DetalleSubcategoriasBO.IdStio

Else

End If

The DetalleSubcategoriasBO is the bussines object for the form.

In the SelectedIndexChanged has this: Me.cboSubcategoria.Requery()

The PopulationDataSourceSettings are: SubCategoriasBO.FillByCategoria(System.Int32) and the PopulateOnFormLoad is in manual (I all rady put this in OnLoad and not works).

Public Sub FillByCategoria(ByVal Sitio As Integer)

'-- Locals

Dim loCommand As New SqlCommand()

'-- Build the query

loCommand.CommandText = "SELECT * FROM SubCategorias_Pub WHERE IdCategoria = @IdCategoria"

'-- Add parameter

loCommand.Parameters.Add("@IdCategoria", SqlDbType.Int)

loCommand.Parameters("@IdCategoria").Value = Subcategoria

'-- Execute command

Me.FillDataTable(loCommand)

End Sub

The ListPopulation event is this:

All you need to understand here is how the relation between the 3 tables works, then in the Combobox.SelectedIndexChanged you have to check the ParentBO.Count > 0, so if there is a record, then you can sent the ParentBO.PKFieldValue to the first parameter e.Parameters(0).Value = Me.ParentBO.PKFieldValue.

In the Categories Combobox SelectedIndexChanged use this code:

Also I believe it is better to use sample with your real entities name, even if it is in Spanish, this way it will make more sense when posting real code .