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Compute method in dataset

Posted on 2008-10-09
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Last Modified: 2012-05-05
I always use compute function to calculate data in some columns in the output datatable variable, so is there a way i can use if i want for example the sum of the top 10 rows in datatable, can i use compute, i donot want to return to the original table
Thanx
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Question by:ashraf_t
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Expert Comment

by:Ted Bouskill
ID: 22684389
The DataSet object actually uses a substantial amount of overhead (memory and CPU)  An aggregate operation can even consume more resources.  I would strongly recommend you do this in the SQL database.
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by:CodeCruiser
CodeCruiser earned 20 total points
ID: 22685078
If you still prefer to do it in the memory then use the select function to select the top 10 rows and then use the compute.
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Author Comment

by:ashraf_t
ID: 22691632
no i want to use the top 10 in the output data not to the original table
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Ted Bouskill earned 30 total points
ID: 22692590
Sorry but I'm more comfortable with C#
DataTable outputTable = SourceTable.Clone();
for(int i=0;i<10;i++)
  outputTable.ImportRow(SourceTable.Rows[i]);

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Author Comment

by:ashraf_t
ID: 22694411
Looping method hmmm, i think this will take time specially if the records are too big
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Expert Comment

by:Ted Bouskill
ID: 22694426
It's either that or do it in the SQL server.  You don't have any other choices.  The Select() method in the DataTable doesn't support aggregate functions.
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Expert Comment

by:Ted Bouskill
ID: 22694436
I manage 5 software developers building web applications.  I wouldn't allow them to do this in a dataset at all.  I'm just trying to answer your question, I don't agree with the strategy.

If you are worried about performance, minimize or avoid using the dataset and use the SqlDataReader instead and define your own collection.
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