Question

im having a problem with the Select() method in my datatable.

If i want to search in my DataTable for multiple patterns (search function)

For string Columns the ‘Like’ works

Select(String.Format("Requester like '%{0}%'", tb_RequesterSearch.Text))

but i also need to check for Numeric patterns in my Numeric column

if i try something like

For Each drOrder As DataRow In dsDatabase.Tables("ProjektImport").Select(String.Format("PONumber like '%{0}%'", convert.toDouble(tb_POSearch.Text)))
     'Do something
Next

i always get the exception, that ‘Like’ is not supportet for Numeric columns.

Is there an equivalent function or a way to cast my column as string (only in the select)?

Thanks in advance

Answer 1

LIKE Expressions don’t work on numeric columns. You could add an additional varchar column to your DataTable via select-clause(before it is filled) or use following LINQ way:

Dim PONumber As Double
If Double.TryParse(tb_POSearch.Text, PONumber) Then
    Dim PONumber_Pattern As String = "*" & PONumber & "*"
    Dim query As IEnumerable(Of DataRow) =
        From row In dsDatabase.Tables("ProjektImport").AsEnumerable()
        Where DirectCast(row("PONumber"), Double).ToString Like PONumber_Pattern
        Select row
    If query.Any Then
        For Each row As DataRow In query
             ' Do whatever you want with this DataRow '
        Next
    End If
End If

Don’t confuse the ADO.NET LIKE Expression with the VB.NET’s LIKE-Operator, that i’ve used here to keep it simple and working. I could also have been used String.Contains or a RegularExpression to achieve the same, it’s a trade-off between performance and flexibility.