XQuery 3 merging two node sequences and de-duplicating
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In XQuery 3.1 (under eXistDB 4.4) I have two functions which return two sets of nodes that describe family relations of a person. The results of the two functions can overlap.
A first function person:person-relationship-as-object("#Guilhem_Faure_SML-AU")
returns:
<person relation="Peire_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Arnald_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Esteve_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Martin_de_Verazilh_SML-AU">
<span class="en">Aunt(s)/Uncle(s)</span>
<span class="fr">Tante(s)/Oncle(s)</span>
</person>
<person relation="Raimund_de_Verazilh_SML-AU">
<span class="en">Aunt(s)/Uncle(s)</span>
<span class="fr">Tante(s)/Oncle(s)</span>
</person>
A second function person:person-relationship-as-subject("#Guilhem_Faure_SML-AU")
returns
<person relation="Arnald_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Peire_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Esteve_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Bernarda_Guilhem_Faure_SML-AU">
<span class="en">Spouse(s)</span>
<span class="fr">Époux/épouse(s)</span>
</person>
Now I want to merge the two sets of nodes into one, and return each distinct node only once.
I attempted a rough SQL-like structure, but failed:
let $x := person:person-relationship-as-object("#Guilhem_Faure_SML-AU")
| person:person-relationship-as-subject("#Guilhem_Faure_SML-AU")
for $y in $x
order by $y/@relation ascending
group by $y/@relation, $y/span[@class="en"], $y/span[@class="fr"]
return $y
I don't think I really understand why the group by
doesn't work here. Moreover, if group by
doesn't do the job, how else can I approach what (I think?) should be a simple exercise in grouping/distinct results?
xquery exist-db
add a comment |
In XQuery 3.1 (under eXistDB 4.4) I have two functions which return two sets of nodes that describe family relations of a person. The results of the two functions can overlap.
A first function person:person-relationship-as-object("#Guilhem_Faure_SML-AU")
returns:
<person relation="Peire_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Arnald_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Esteve_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Martin_de_Verazilh_SML-AU">
<span class="en">Aunt(s)/Uncle(s)</span>
<span class="fr">Tante(s)/Oncle(s)</span>
</person>
<person relation="Raimund_de_Verazilh_SML-AU">
<span class="en">Aunt(s)/Uncle(s)</span>
<span class="fr">Tante(s)/Oncle(s)</span>
</person>
A second function person:person-relationship-as-subject("#Guilhem_Faure_SML-AU")
returns
<person relation="Arnald_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Peire_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Esteve_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Bernarda_Guilhem_Faure_SML-AU">
<span class="en">Spouse(s)</span>
<span class="fr">Époux/épouse(s)</span>
</person>
Now I want to merge the two sets of nodes into one, and return each distinct node only once.
I attempted a rough SQL-like structure, but failed:
let $x := person:person-relationship-as-object("#Guilhem_Faure_SML-AU")
| person:person-relationship-as-subject("#Guilhem_Faure_SML-AU")
for $y in $x
order by $y/@relation ascending
group by $y/@relation, $y/span[@class="en"], $y/span[@class="fr"]
return $y
I don't think I really understand why the group by
doesn't work here. Moreover, if group by
doesn't do the job, how else can I approach what (I think?) should be a simple exercise in grouping/distinct results?
xquery exist-db
return functx:distinct-deep($x) does the job, without grouping...
– jbrehr
Nov 23 '18 at 16:40
add a comment |
In XQuery 3.1 (under eXistDB 4.4) I have two functions which return two sets of nodes that describe family relations of a person. The results of the two functions can overlap.
A first function person:person-relationship-as-object("#Guilhem_Faure_SML-AU")
returns:
<person relation="Peire_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Arnald_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Esteve_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Martin_de_Verazilh_SML-AU">
<span class="en">Aunt(s)/Uncle(s)</span>
<span class="fr">Tante(s)/Oncle(s)</span>
</person>
<person relation="Raimund_de_Verazilh_SML-AU">
<span class="en">Aunt(s)/Uncle(s)</span>
<span class="fr">Tante(s)/Oncle(s)</span>
</person>
A second function person:person-relationship-as-subject("#Guilhem_Faure_SML-AU")
returns
<person relation="Arnald_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Peire_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Esteve_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Bernarda_Guilhem_Faure_SML-AU">
<span class="en">Spouse(s)</span>
<span class="fr">Époux/épouse(s)</span>
</person>
Now I want to merge the two sets of nodes into one, and return each distinct node only once.
I attempted a rough SQL-like structure, but failed:
let $x := person:person-relationship-as-object("#Guilhem_Faure_SML-AU")
| person:person-relationship-as-subject("#Guilhem_Faure_SML-AU")
for $y in $x
order by $y/@relation ascending
group by $y/@relation, $y/span[@class="en"], $y/span[@class="fr"]
return $y
I don't think I really understand why the group by
doesn't work here. Moreover, if group by
doesn't do the job, how else can I approach what (I think?) should be a simple exercise in grouping/distinct results?
xquery exist-db
In XQuery 3.1 (under eXistDB 4.4) I have two functions which return two sets of nodes that describe family relations of a person. The results of the two functions can overlap.
A first function person:person-relationship-as-object("#Guilhem_Faure_SML-AU")
returns:
<person relation="Peire_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Arnald_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Esteve_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Martin_de_Verazilh_SML-AU">
<span class="en">Aunt(s)/Uncle(s)</span>
<span class="fr">Tante(s)/Oncle(s)</span>
</person>
<person relation="Raimund_de_Verazilh_SML-AU">
<span class="en">Aunt(s)/Uncle(s)</span>
<span class="fr">Tante(s)/Oncle(s)</span>
</person>
A second function person:person-relationship-as-subject("#Guilhem_Faure_SML-AU")
returns
<person relation="Arnald_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Peire_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Esteve_Faure_SML-AU">
<span class="en">Sibling(s)</span>
<span class="fr">Frère(s)/sœur(s)</span>
</person>
<person relation="Bernarda_Guilhem_Faure_SML-AU">
<span class="en">Spouse(s)</span>
<span class="fr">Époux/épouse(s)</span>
</person>
Now I want to merge the two sets of nodes into one, and return each distinct node only once.
I attempted a rough SQL-like structure, but failed:
let $x := person:person-relationship-as-object("#Guilhem_Faure_SML-AU")
| person:person-relationship-as-subject("#Guilhem_Faure_SML-AU")
for $y in $x
order by $y/@relation ascending
group by $y/@relation, $y/span[@class="en"], $y/span[@class="fr"]
return $y
I don't think I really understand why the group by
doesn't work here. Moreover, if group by
doesn't do the job, how else can I approach what (I think?) should be a simple exercise in grouping/distinct results?
xquery exist-db
xquery exist-db
edited Nov 23 '18 at 16:00
jbrehr
asked Nov 23 '18 at 15:02
jbrehrjbrehr
134212
134212
return functx:distinct-deep($x) does the job, without grouping...
– jbrehr
Nov 23 '18 at 16:40
add a comment |
return functx:distinct-deep($x) does the job, without grouping...
– jbrehr
Nov 23 '18 at 16:40
return functx:distinct-deep($x) does the job, without grouping...
– jbrehr
Nov 23 '18 at 16:40
return functx:distinct-deep($x) does the job, without grouping...
– jbrehr
Nov 23 '18 at 16:40
add a comment |
1 Answer
1
active
oldest
votes
With XQuery and group by
, the variable $y
in your return
clause is bound to the whole group you have created so to eliminate duplicates you need to use return $y[1]
. See https://www.w3.org/TR/xquery-31/#id-group-by which says
In the post-grouping tuple generated for a given group, each
non-grouping variable is bound to a sequence containing the
concatenated values of that variable in all the pre-grouping tuples
that were assigned to that group.
and then
This behavior may be surprising to SQL programmers, since SQL reduces
the equivalent of a non-grouping variable to one representative value.
add a comment |
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1 Answer
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active
oldest
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
With XQuery and group by
, the variable $y
in your return
clause is bound to the whole group you have created so to eliminate duplicates you need to use return $y[1]
. See https://www.w3.org/TR/xquery-31/#id-group-by which says
In the post-grouping tuple generated for a given group, each
non-grouping variable is bound to a sequence containing the
concatenated values of that variable in all the pre-grouping tuples
that were assigned to that group.
and then
This behavior may be surprising to SQL programmers, since SQL reduces
the equivalent of a non-grouping variable to one representative value.
add a comment |
With XQuery and group by
, the variable $y
in your return
clause is bound to the whole group you have created so to eliminate duplicates you need to use return $y[1]
. See https://www.w3.org/TR/xquery-31/#id-group-by which says
In the post-grouping tuple generated for a given group, each
non-grouping variable is bound to a sequence containing the
concatenated values of that variable in all the pre-grouping tuples
that were assigned to that group.
and then
This behavior may be surprising to SQL programmers, since SQL reduces
the equivalent of a non-grouping variable to one representative value.
add a comment |
With XQuery and group by
, the variable $y
in your return
clause is bound to the whole group you have created so to eliminate duplicates you need to use return $y[1]
. See https://www.w3.org/TR/xquery-31/#id-group-by which says
In the post-grouping tuple generated for a given group, each
non-grouping variable is bound to a sequence containing the
concatenated values of that variable in all the pre-grouping tuples
that were assigned to that group.
and then
This behavior may be surprising to SQL programmers, since SQL reduces
the equivalent of a non-grouping variable to one representative value.
With XQuery and group by
, the variable $y
in your return
clause is bound to the whole group you have created so to eliminate duplicates you need to use return $y[1]
. See https://www.w3.org/TR/xquery-31/#id-group-by which says
In the post-grouping tuple generated for a given group, each
non-grouping variable is bound to a sequence containing the
concatenated values of that variable in all the pre-grouping tuples
that were assigned to that group.
and then
This behavior may be surprising to SQL programmers, since SQL reduces
the equivalent of a non-grouping variable to one representative value.
edited Nov 23 '18 at 20:41
answered Nov 23 '18 at 19:55
Martin HonnenMartin Honnen
113k66279
113k66279
add a comment |
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return functx:distinct-deep($x) does the job, without grouping...
– jbrehr
Nov 23 '18 at 16:40