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VB.NET: SqlDataReader + DataTable : Copying returned multiple recordset into a single recordsets

Posted on 2011-02-15
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Last Modified: 2014-11-12
In order to improve performance on my SQL Azure database, I want to combine several queries together.

SELECT * FROM Table1;
SELECT * FROM Table2;
SELECT * FROM Table3;

I have three DataTable objects that I would like to copy the returned data.

Dim dtTable1 As New DataTable
Dim dtTable2 As New DataTable
Dim dtTable3 As New DataTable

When I load the DataTable object with the recordset, it appears to include all returned recordsets, rather than just one.

Example:

dtTable1.Load(Rs)

Rs.NextResult
dtTable2.Load(Rs)

Rs.NextResult
dtTable3.Load(Rs)

After several recordsets are copied into the DataTables, it errors.

A first chance exception of type 'System.InvalidOperationException' occurred in System.Data.dll

If I run the queries separately, I don't receive the error.  I am trying to accomplish:

  o Single, quick query to the Azure server using 1 query
  o Update the DataTable objects with the returned recordsets, separately

Is there a way to "copy" out a single recordset to a new object without the other recordsets included?

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Question by:Officedoxs
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3 Comments
 
LVL 53

Expert Comment

by:Dhaest
ID: 34904536
Don't you have the possibility to query the tables at once by using a union ?

>> A first chance exception of type 'System.InvalidOperationException' occurred in System.Data.dll

Where do you get that error ?
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LVL 83

Accepted Solution

by:
CodeCruiser earned 500 total points
ID: 34906047
Given that the Load method of DataTable internal calls the NextResult,
http://platinumdogs.wordpress.com/2009/05/14/sqldatareader-datatable-and-multiple-resultsets/

you have to use an alternative. I think you have two options

1) Use DataSet.Load
2) Use a DataAdapter.Fille(DataSet) which would create separate DataTable objects for each resultset.
0
 

Author Closing Comment

by:Officedoxs
ID: 34908464
From the referenced link, I can use the DataTable object successfully.  It's just that I need to remove the Rs.NextResult lines in my code, the .Load does it automatically.
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