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  • Sub query pass through

    Occasionally in forums and on client sites I see conditional subqueries in statements. This is where the developer has decided that it is only necessary to process some data under a certain condition.  By way of example, something like this : Create Procedure GetOrder @SalesOrderId integer, @CountDetails...
    Posted to SQL and the like (Weblog) by Anonymous on Fri, Mar 22 2013
  • Denali Paging–Key seek lookups

    In my previous post “ Denali Paging – is it win.win ? ” I demonstrated the use of using the Paging functionality within Denali.  On reflection,  I think i may of been a little unfair and should of continued always planned to continue my investigations to the next step. In Pauls article , he...
    Posted to SQL and the like (Weblog) by Dave Ballantyne on Fri, Nov 19 2010
  • Denali Paging–Is it win/win ?

    UPDATE : 2012-07-26 : My latest commentry of the paging subject can be found here : http://sqlblogcasts.com/blogs/sqlandthelike/archive/2012/04/26/offset-without-offset.aspx I'm not one for automatically poo-pooing new ideas, new practices and new technology. Rather I like to take a measured view...
    Posted to SQL and the like (Weblog) by Dave Ballantyne on Wed, Nov 10 2010
  • An impossible case

    In a previous blog entry ( Inconsistent NullIf behaviour ), Jeff Moden and Dan Halliday ( twitter ) both made a very similar observation. When executing this code Code Snippet select top ( 10 ) abs ( checksum ( newid ()))% 4 from sys . objects the only possible values returned can be 0,1,2 or 3. Anything...
    Posted to SQL and the like (Weblog) by Dave Ballantyne on Mon, Sep 6 2010
  • Inconsistent NullIF Behaviour ?

    NullIf can be a very handy function sometimes. For those who have not used it, if the result of the two parameters are equal then null is returned. So if we execute : Code Snippet Select nullif ( 10 , 10 ) as Result1 Select nullif ( 10 , 9 ) as Result2 We get the result of For some test data, I required...
    Posted to SQL and the like (Weblog) by Dave Ballantyne on Fri, Aug 6 2010
  • Using a UDF as a SARG. Make a hash of it!

    I am somewhat uncomfortable blogging this, as I feel that it falls into “Polish a turd” category. Having said that, it is a particularly ugly turd and it does polish up rather well. Though as the saying goes, it is still a turd. The evils and inadequacies of UDF (User Defined Functions) in SqlServer...
    Posted to SQL and the like (Weblog) by Dave Ballantyne on Fri, Jul 2 2010
  • Challenge 19 – An Explanation of a Query

    I have received a number of requests for an explanation of my winning query of TSQL Challenge 19 . This involved traversing a hierarchy of employees and rolling a count of orders from subordinates up to superiors. The first concept I shall address is the hierarchyId , which is constructed within the...
    Posted to SQL and the like (Weblog) by Dave Ballantyne on Thu, May 27 2010
  • BUG - Use of ranking functions result in an inefficient query plan

    In SQL2005 (9.00.4207.00), if you use a ranking function within a view or CTE, then an inefficient query plan can be produced. First off in Adventure works create this index Create Index idxLastName on Person . Contact ( LastName ) and then consider these similar queries: select ContactId , LastName...
    Posted to SQL and the like (Weblog) by Dave Ballantyne on Tue, Sep 8 2009
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