DataTable.Compute() question

  • Thread starter Thread starter SpaceMarine
  • Start date Start date
S

SpaceMarine

hello,

i have a big datable of a bunch of stuff. i am interested in getting
row counts that match certain criteria.

currently i do this by creating a new DataView for each criteria, and
getting its .RowCount. like so:

dv = New DataView(dt, "Type = 2", "Type",
DataViewRowState.CurrentRows)
total = dv.Count
writer.WriteLine(String.Format("Lines of Type 2: {0}.", total))

....that works, but i was wondering -- is there a way to use the
DataTable.Compute() method to do this? i had tried something like
this, but it didnt work:

Dim oTotal As Object = dt.Compute("Count(*)", "Type = 2")

....this doesnt work because the aggregate function Count() isnt
designed to work this way. but is there something that is?

thanks!
matt
 
Matt,

Maybe there is, however what you think to win with that, in my idea is your
method very inventive and most probably the fastest you can get.

Cor
 
No, you can't use Compute for this one.
As an alternative (similar to your solution) you might use DataTable.Select
method.
 
hello,

i have a big datable of a bunch of stuff. i am interested in getting
row counts that match certain criteria.

currently i do this by creating a new DataView for each criteria, and
getting its .RowCount. like so:

dv = New DataView(dt, "Type = 2", "Type",
DataViewRowState.CurrentRows)
total = dv.Count
writer.WriteLine(String.Format("Lines of Type 2: {0}.", total))

...that works, but i was wondering -- is there a way to use the
DataTable.Compute() method to do this? i had tried something like
this, but it didnt work:

Dim oTotal As Object = dt.Compute("Count(*)", "Type = 2")

...this doesnt work because the aggregate function Count() isnt
designed to work this way. but is there something that is?

thanks!
matt
Click to expand...

Can't you use dt.Rows.Length

And I don't think DataTable.Select provides too much options either
 
Amit said:
Can't you use dt.Rows.Length
Click to expand...

No. He needs to count *filtered* rows, not all rows.
And I don't think DataTable.Select provides too much options either
Click to expand...

No, it doesn't - it is quite same as creating a DataView, it is just less
code in this scenario.[/QUOTE]
 
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