Why is this Xquery expression returning a null value?












2















I want to get the maximum value for an attribute. I have the following statement:




let $posts := doc("Posts.xml")/posts/row[./@OwnerUserId = $user/@Id]



let $maxScore := fn:max(xs:integer($posts/row/@Score))




When I want to return maxScore, it shows up as an empty value. Upon further tinkering, the following:




Return $posts/row/@Score




Also shows up as empty, even though I know each row has a 'Score' attribute



I've been fighting with this for over an hour, any help is appreciated






xpath xquery







share|improve this question





























    2















    I want to get the maximum value for an attribute. I have the following statement:




    let $posts := doc("Posts.xml")/posts/row[./@OwnerUserId = $user/@Id]



    let $maxScore := fn:max(xs:integer($posts/row/@Score))




    When I want to return maxScore, it shows up as an empty value. Upon further tinkering, the following:




    Return $posts/row/@Score




    Also shows up as empty, even though I know each row has a 'Score' attribute



    I've been fighting with this for over an hour, any help is appreciated






    xpath xquery







    share|improve this question



























      2












      2








      2








      I want to get the maximum value for an attribute. I have the following statement:




      let $posts := doc("Posts.xml")/posts/row[./@OwnerUserId = $user/@Id]



      let $maxScore := fn:max(xs:integer($posts/row/@Score))




      When I want to return maxScore, it shows up as an empty value. Upon further tinkering, the following:




      Return $posts/row/@Score




      Also shows up as empty, even though I know each row has a 'Score' attribute



      I've been fighting with this for over an hour, any help is appreciated






      xpath xquery







      share|improve this question
















      I want to get the maximum value for an attribute. I have the following statement:




      let $posts := doc("Posts.xml")/posts/row[./@OwnerUserId = $user/@Id]



      let $maxScore := fn:max(xs:integer($posts/row/@Score))




      When I want to return maxScore, it shows up as an empty value. Upon further tinkering, the following:




      Return $posts/row/@Score




      Also shows up as empty, even though I know each row has a 'Score' attribute



      I've been fighting with this for over an hour, any help is appreciated






      xpath xquery




      xpath xquery






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Nov 15 '18 at 3:47









      Mads Hansen

      44.2k1093121




      44.2k1093121










      asked Nov 14 '18 at 23:59









      Francisco José LetterioFrancisco José Letterio

      1415




      1415
























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          You are selecting the row elements that meet the criteria of your predicate. So, the $posts variable will have a sequence of row elements.



          If you want to select the @Score from each of the row elements in the $posts variable, your XPath should be: $posts/@Score



          It would be less confusing if you named the variable $rows.



          Or, change the XPath to actually select posts elements:



          let $posts := doc("Posts.xml")/posts[row/@OwnerUserId = $user/@Id]
          
let $maxScore := fn:max(xs:integer($posts/row/@Score))





          share|improve this answer























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            You are selecting the row elements that meet the criteria of your predicate. So, the $posts variable will have a sequence of row elements.



            If you want to select the @Score from each of the row elements in the $posts variable, your XPath should be: $posts/@Score



            It would be less confusing if you named the variable $rows.



            Or, change the XPath to actually select posts elements:



            let $posts := doc("Posts.xml")/posts[row/@OwnerUserId = $user/@Id]
            
let $maxScore := fn:max(xs:integer($posts/row/@Score))





            share|improve this answer




























              1














              You are selecting the row elements that meet the criteria of your predicate. So, the $posts variable will have a sequence of row elements.



              If you want to select the @Score from each of the row elements in the $posts variable, your XPath should be: $posts/@Score



              It would be less confusing if you named the variable $rows.



              Or, change the XPath to actually select posts elements:



              let $posts := doc("Posts.xml")/posts[row/@OwnerUserId = $user/@Id]
              
let $maxScore := fn:max(xs:integer($posts/row/@Score))





              share|improve this answer


























                1












                1








                1







                You are selecting the row elements that meet the criteria of your predicate. So, the $posts variable will have a sequence of row elements.



                If you want to select the @Score from each of the row elements in the $posts variable, your XPath should be: $posts/@Score



                It would be less confusing if you named the variable $rows.



                Or, change the XPath to actually select posts elements:



                let $posts := doc("Posts.xml")/posts[row/@OwnerUserId = $user/@Id]
                
let $maxScore := fn:max(xs:integer($posts/row/@Score))





                share|improve this answer













                You are selecting the row elements that meet the criteria of your predicate. So, the $posts variable will have a sequence of row elements.



                If you want to select the @Score from each of the row elements in the $posts variable, your XPath should be: $posts/@Score



                It would be less confusing if you named the variable $rows.



                Or, change the XPath to actually select posts elements:



                let $posts := doc("Posts.xml")/posts[row/@OwnerUserId = $user/@Id]
                
let $maxScore := fn:max(xs:integer($posts/row/@Score))






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 15 '18 at 3:42









                Mads HansenMads Hansen

                44.2k1093121




                44.2k1093121






























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