DataTable Compute Method

[Guest]

Hi!

There are 3 DaTables in my DataSet, which 1 is the Master and 2 are
Children. I've set the relations and everything is working fine. But when I
try to use the Compute method I receive a strange error and I can't find the
solution.

dtsMovES.Tables("MovES").Compute("COUNT(Child(MovES_To_MovESItens).CodMovESItens)", String.Empty)

ERROR:
An unhandled exception of type 'System.Data.EvaluateException' occured in
system.windows.forms.dll
Additional information: Is not possible to evaluate. Expression
'Count(child([MovES_To_MovESItens]).[CodMovESItens])' is not aggregate.

I'm sure about the relations/tables/fields' names.
Please I need another sorte of eyes to look at it.

Thanks!

 

[Vasco Veiga [MS]]

If i understand correctly, you want to compute the nb of "itens" for a given
MovEs record.

The easiest way is to add an expression column (ex: ItensCount) on the MovEs
table with the expression "COUNT(Child(MovES_To_MovESItens).CodMovESItens)".
This will give you the nb of itens for each MovEs record.
dtsMovEs.Columns.Add( "ItensCount" ).Expression = "

Then you can also do
dtsMovES.Tables("MovES").Compute("SUM(ItensCount)", String.Empty)
which will return you the total nb of Itens for the MovEs records.

You cannot use DataTable.Compute because it does not allow you to aggregate
over non local columns.