Category Archives: Community

Articles on community events.

#0373 – SQL Server – Interview Questions – Parameters required for server-side paging mechanisms


For a mid-level SQL developer profile, this is one of my favourite interview questions if their current projects involve some sort of paging mechanism while displaying results on a grid.

What is the minimum number of parameters that your stored procedure needs to implement server-side paging?

Despite the multiple blog posts around this topic, this question surprisingly still stumps most of the developers.

The answer is quite simple – at a basic level, you absolutely need two (2) input parameters on your stored procedure to implement server-side paging:

  1. The page number
  2. The page size, i.e. the number of records to be displayed on each page

Of course, the implementation may vary – one can have multiple additional parameters like the sort column and the sort order, but at the very minimum one needs the two (2) parameters listed above.

For reference, here is a sample implementation (for SQL Server 2008 R2 and SQL Server 2012):

USE AdventureWorks2012 ;
GO
SET NOCOUNT ON ;

DECLARE @pageSize INT = 100 ;
DECLARE @pageNumber INT = 3 ;

--SQL 2008 R2 Method
--Source Data, fetched with paging
;
WITH    SourceDataCTE ( CarrierTrackingNumber, SalesOrderId, TotalShipmentValue, RowNumber )
          AS ( SELECT   sod.CarrierTrackingNumber,
                        sod.SalesOrderId,
                        SUM(sod.LineTotal) AS TotalShipmentValue,
                        ROW_NUMBER() OVER ( ORDER BY sod.CarrierTrackingNumber, sod.SalesOrderId ) AS RowNumber
               FROM     Sales.SalesOrderHeader AS soh
                        INNER JOIN Sales.SalesOrderDetail AS sod ON sod.SalesOrderID = soh.SalesOrderID
               WHERE    soh.ShipDate IS NOT NULL
                        AND sod.CarrierTrackingNumber IS NOT NULL
               GROUP BY sod.CarrierTrackingNumber,
                        sod.SalesOrderId
             )
    SELECT TOP ( @pageSize )
            sdCTE.CarrierTrackingNumber,
            sdCTE.SalesOrderId,
            sdCTE.TotalShipmentValue,
                     sdCTE.RowNumber
    FROM    SourceDataCTE AS sdCTE
    WHERE   sdCTE.RowNumber BETWEEN ( ( @pageNumber * @pageSize ) + 1 )
                            AND     ( ( @pageNumber + 1 ) * @pageSize ) ;

--SQL 2012 Method
SELECT   sod.CarrierTrackingNumber,
        sod.SalesOrderId,
        --SUM(sod.LineTotal) OVER ( ORDER BY sod.CarrierTrackingNumber, sod.SalesOrderId ) AS TotalShipmentValue,
        SUM(sod.LineTotal) AS TotalShipmentValue,
        ROW_NUMBER() OVER ( ORDER BY sod.CarrierTrackingNumber, sod.SalesOrderId ) AS RowNumber
FROM     Sales.SalesOrderHeader AS soh
        INNER JOIN Sales.SalesOrderDetail AS sod ON sod.SalesOrderID = soh.SalesOrderID
WHERE    soh.ShipDate IS NOT NULL
        AND sod.CarrierTrackingNumber IS NOT NULL
GROUP BY sod.CarrierTrackingNumber,
        sod.SalesOrderId
ORDER BY sod.CarrierTrackingNumber
OFFSET (@pageNumber * @pageSize) ROWS
FETCH NEXT (@pageSize) ROWS ONLY
GO

Here’s the result of the code snippet provided above:

Shows the output of the various server-side paging mechanisms available for Microsoft SQL Server

SQL Server Paging Mechanisms

Until we meet next time,
Be courteous. Drive responsibly.

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#0369 – Visual Studio Solutions – SSIS and Coded UI projects – encounter “System.ArgumentNullException” and tests do not build successfully


Recently, we undertook a project to write a couple of automation tools for the utilities that we use to move data around.

The automation solution involved a couple of SSIS packages that created a few data views, generated some key columns and cross-referenced records with predefined static data to facilitate data comparison. In addition, we also wrote a couple of Coded UI tests which would read configuration parameters from a simple Excel file and run through the utilities so that they can run independently without any need of human interaction.

The issue

Unfortunately, it seems that at least in Visual Studio 2012, one cannot have both – an SSIS project and a Coded UI project. This is because the Coded UI tests fail to build with a “System.ArgumentNullException” error.

Here are the simple steps to reproduce the issue:

  1. Launch VS2012
  2. In an new solution, add a new Integration Services project. Leave defaults and save the solution
  3. In this solution, add a new Coded UI Test project. Leave defaults and save the solution. The solution now has the 2 projects as required
  4. Go to Test -> Windows -> Test Explorer
  5. In the solution explorer, right click on the solution and choose “Build Solution”
  6. Build fails unexpectedly with the following error:
System.ArgumentNullException: Value cannot be null.
Parameter name: source
at Microsoft.VisualStudio.Shell.ValidateArg.NotNull[T](T arg, String parameterName)
at Microsoft.VisualStudio.Shell.ValidateArg.NotNullOrEmpty[T](IEnumerable`1 arg, String parameterName)
at Microsoft.VisualStudio.Shell.Interop.VSProjectExtensions.CompareNormalizedPath(String source, String target)
at Microsoft.VisualStudio.Shell.Interop.VSProjectExtensions.GetKeyOutputForIVsOutputGroup(IVsOutputGroup outputGroup)
at Microsoft.VisualStudio.Shell.Interop.VSProjectExtensions.GetProjectOutputPath(IVsProjectCfg2 projectConfig, String groupName)
at Microsoft.VisualStudio.Shell.Interop.VSProjectExtensions.GetKeyOutputForGroup(IVsSolutionBuildManager buildManager, IVsProject project, String groupName)
at Microsoft.VisualStudio.TestWindow.VsAdapters.VsTestContainer.get_Source()
at Microsoft.VisualStudio.TestWindow.VsAdapters.VsTestContainer.CreateTimeStamp()
at Microsoft.VisualStudio.TestWindow.VsAdapters.VsTestContainer..ctor(ITestContainerDiscoverer discoverer, ILogger log, IVsProject project, IServiceProvider serviceProvider, IVsAppContainerUtilities appContainerUtilities)
at Microsoft.VisualStudio.TestWindow.VsAdapters.VsProjectOutputContainerDiscoverer.<get_TestContainers>b__0(IVsProject p)
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at System.Linq.Enumerable.WhereEnumerableIterator`1.MoveNext()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at Microsoft.VisualStudio.TestWindow.Controller.TestContainerDiscovererExtension.GetSortedContainers(ITestContainerDiscoverer discoverer)
at Microsoft.VisualStudio.TestWindow.Controller.TestContainerProvider.GetContainersFromDiscoverer(ITestContainerDiscoverer discoverer)

The Workaround

The workaround to build and run the Coded UI tests is to simply unload (removal of the project is not necessary) the SSIS project(s) for the time being. Once the Coded UI tests are done, the SSIS project(s) can be loaded back into the solution before checking it back into source control.

MS Connect Case

While the workaround is simple enough, it can be slightly inconvenient when there are multiple team members who consume the solution. I therefore wrote up a Connect case for this issue (ID# 2194579). Here’s the link: https://connect.microsoft.com/VisualStudio/feedback/details/2194579/solution-with-both-coded-ui-and-integration-services-projects-encounters-system-argumentnullexception-and-tests-do-not-build-successfully

If you encounter the same issue, or if you believe it should be fixed, please “up” vote on the MS connect item linked above.

Until we meet next time,
Be courteous. Drive responsibly.