CODEWITHSUNDEEP
arrayscomparexquery
Asdemuertes
Asdemuertes

Reputation: 323

Xquery, compare an element in an array to the next one

Having an array with distinct values, how can i compare in a query two elements who share a same condition and are one next to the other,sorry for the bad english, it's not my mother tongue Here's the xml:

<prac1516>
    <torns>
        <torn codi="A" nom="Matí" preu="100" />
        <torn codi="B" nom="Tarda" preu="150" />
        <torn codi="C" nom="Nit" preu="200" />
    </torns>

    <tipus>
        <espec id="e1" torn="C">Musica</espec>
        <espec id="e2">Cine</espec>
        <espec id="e3" torn="B">Xerrada</espec>
        <espec id="e4">Festa Infantil</espec>
    </tipus>

    <clients>
        <client id="1">Marti</client>
        <client id="2">Jana</client>
        <client id="3">Edu</client>
        <client id="4">Berta</client>
        <client id="5">Laia</client>    
        <client id="6">Santi</client>
        <client id="7">Pau</client>
        <client id="8">Mia</client> 
    </clients>

    <calendari>
        <reserva client="1" data="2016-01-01" torn="A" espec="e2" />
        <reserva client="2" data="2016-01-01" torn="B" espec="e3" />
        <reserva client="3" data="2016-01-02" torn="C" espec="e3" />
        <reserva client="4" data="2016-01-03" torn="A" espec="e2" />
        <reserva client="4" data="2016-01-03" torn="B" espec="e4" />
        <reserva client="2" data="2016-01-03" torn="C" espec="e4" />
        <reserva client="8" data="2016-01-04" torn="A" espec="e3" />
        <reserva client="4" data="2016-01-04" torn="C" espec="e3" />
        <reserva client="3" data="2016-01-05" torn="A" espec="e1" />
        <reserva client="7" data="2016-01-05" torn="B" espec="e1" />
        <reserva client="2" data="2016-01-06" torn="A" espec="e1" />
        <reserva client="1" data="2016-01-06" torn="B" espec="e2" />
        <reserva client="3" data="2016-01-06" torn="B" espec="e2" />
        <reserva client="4" data="2016-01-08" torn="B" espec="e3" />
        <reserva client="7" data="2016-01-08" torn="C" espec="e2" />
        <reserva client="8" data="2016-01-09" torn="A" espec="e2" />
        <reserva client="9" data="2016-01-09" torn="B" espec="e4" />
        <reserva client="2" data="2016-01-09" torn="C" espec="e4" />
        <reserva client="2" data="2016-01-10" torn="A" espec="e3" />
        <reserva client="1" data="2016-01-10" torn="B" espec="e2" />
        <reserva client="1" data="2016-01-10" torn="C" espec="e1" />
    </calendari>

</prac1516>

I want to see the dates (data) in which there's a torn a and after that a torn B, or a torn B and after that a torn C

I thought that this would do what i want, but nope! : 

let $w :=
  for $x in //reserva
  let $d := //reserva/@data
  return $d
for $r in (1 to 21)
where (//reserva[@data=$w[$r]]/@torn='A' and  //reserva[@data=$w[$r+1]]/@torn='B') or (//reserva[@data=$w[$r]]/@torn='B'and  //reserva[@data=$w[$r+1]]/@torn='C')
return $w[$r]

Upvotes: 1

Views: 428

Answers (1)

har07
har07

Reputation: 89305

You can get the next reserva element by using following-sibing::reserva[1], like so :

for $r in //reserva
let $next_r := $r/following-sibling::reserva[1]   
where 
    ($r/@torn eq 'A' and $next_r/@torn eq 'B')
        or
    ($r/@torn eq 'B' and $next_r/@torn eq 'C')
return $r/@data

Upvotes: 1

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