|The solution given by Bernhard Hiller works fine.
Another option is in the
DataSet designer or programmatically, create a relation between
Region DataTables like
Relation Name: CountryRegion
Parent Table: Country, primary key: CountryID
Child Table: Region, Foreign key: CountryID
Dim CountryBindingSource As New BindingSource(DataSet1, "Country")
Dim RegionBindingSource As New BindingSource(CountryBindingSource, "CountryRegion")
comboBox1.DataSource = CountryBindingSource
comboBox1.DisplayMember = "Country"
comboBox1.ValueMember = "CountryID"
comboBox2.DataSource = RegionBindingSource
comboBox2.DisplayMember = "Region"
comboBox2.ValueMember = "RegionID"