Create keys on datatables

[BSWhipp]

I have a datatable that I need to find information in. I can not use a primary key since the columns do have duplicate data. How can I search in the datatable for a string. Is there a way to setup indexes?

[BSWhipp]

Found it.

'Find a description - Gets the Last rev description
Dim found() As DataRow
Dim expression As String = "fpartno = '" & lcPartno & "'"
'Dim expression As String = "fpartno = '0904-D34N'" 'For Testing
found = datatable.Select(expression)

If found.GetUpperBound(0) > 0 Then
lcDescript = found(found.GetUpperBound(0)).ItemArray(2).ToString()
End If

[Shaggy Hiker]

Yeah, that's one way. Another way would be to set the RowFilter property of the default dataview, which will returns a subset DataView. Another way would be to use LINQ, which allows you to essentially write queries against the datatable. A fourth way would be to iterate through the rows checking the fields. Interestingly, that fourth option, though it takes more code, is faster than any of the others, including the Select that you used.

There's also a fifth option that can be even faster, but ignore that one, because it is highly specialized and situational.

[jmcilhinney]

Are you aware that this:

                If found.GetUpperBound(0) > 0 Then
                    lcDescript = found(found.GetUpperBound(0)).ItemArray(2).ToString()
                End If

is getting data from the second row if and only if there are at least two rows?

[BSWhipp]

Yes, I want to retrieve that data when i found what was in column 1.

[jmcilhinney]

But what if there is only one matching row? Are you not interested in that data? Maybe you aren't and that's fine, but that would be unusual so I just wanted to make sure that it wasn't a mistake. Most people would use Length rather than GetUpperBound in that particular situation to determine whether there are any rows at all rather than determine whether there are at least two rows.