[RESOLVED] vb.net improve programs

ok i guess this is too much difficult for me..
stations it's correctly filled but combobox1 is empty.
i keep on matrix.
it takes longer,very hard to inquiry but it works
many thanks to all of you

you can create a Access .mdb and Access doesn't have to be Installed
on your Company PC

Code:

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Private Sub Button4_Click(sender As System.Object, e As System.EventArgs) Handles Button4.Click
        'Add the COM Reference, "Microsoft ADO Ext. 6.0 for DLL and Security"
        ' create the empty DB file
        Dim cat As New ADOX.Catalog()
        cat.Create("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\Berichte\Backup.mdb")
        cat = Nothing
    End Sub

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as easy as that

Quote:

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Originally Posted by jmcilhinney

It's not going to be a SQL query because you're not querying a database. Let's say that you have a DataTable with the names of stations in Partenza and Arrivo columns and you want to list distinct values in alphabetical order. One option is to use a LINQ query:

vb.net Code:

Dim partenzaStations = table.AsEnumerable().Select(Function(row) row.Field(Of String)("Partenza"))
Dim arrivoStations = table.AsEnumerable().Select(Function(row) row.Field(Of String)("Arrivo"))
Dim stations = partenzaStations.Concat(arrivoStations).Distinct().OrderBy(Function(s) s).ToArray()
 
stationComboBox.DataSource = stations

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it works only if i don't order the list,otherwise the combobox it wont' be loaded !!
i guess it's due the first value is nothing.
but the where condition can not be applyied in the query.so strange

at the end i solved in this way :

Code:

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Dim partenzaStations = From n In treno1.AsEnumerable()
                                  Where n.Field(Of String)("Partenza") IsNot Nothing
                                  Select n.Field(Of String)("Partenza")

                                  Dim arrivoStations = From n In treno1.AsEnumerable()
                                  Where n.Field(Of String)("Arrivo") IsNot Nothing
                                      Select n.Field(Of String)("Arrivo")

                                Dim stations = partenzaStations.Concat(arrivoStations).Distinct().OrderBy(Function(s) s).ToArray()

                              ComboBox1.DataSource = stations.ToArray
                                ComboBox1.SelectedIndex = -1

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maybe it will help somebody else