Join Example (1)

bc#0.bookstore#1

bc#0.bookstore#1.fiction#2

bc#0.bookstore#1.fiction#2.sci-fi#3

...

$A=*[d-join[return(children(.))](.)](x)=

//*?

bc#0

$B=select[“book”](d-join[return(children(.))]($A))=

//*?/book

bc#0.bs#1.f#2.sf#3.b#4

bc#0.bs#1.f#2.fa#8.mi#9.b#10

...

$C=d-join[return(children(.))]($B)=//*?/book?/*

bc#0.bs#1.f#2.sf#3.b#4.isbn#5

bc#0.bs#1.f#2.sf#3.b#4.title#6

...

$D=varbind[$i,select[“isbn”](children(.))]($B)=

//*?/book[$i:=isbn]?

bc#0.bs#1.f#2.sf#3.b#4<$i,isbn#5>

bc#0.bs#1.f#2.fa#8.mi#9.b#10<$i,isbn#11>

...

$F=d-join(select[

select[“isbn”](d-join[children(.)]

(select[“boughtbooks”](d-join[children(.)](.)))=

= varget[$i](.)](“$E”)]($D)=

//*?/book[$i:=isbn]?/

(//*?/customer[boughtbooks/isbn=$i])

$E=select[“customer”](d-join[children(.)]

(*[d-join[return(children(.))](.)](d-join[root(.)]($D)))=//*?/customer

customers#14.customer#15

customers#14.customer#20

bc#0.bs#1.f#2.sf#3.b#4.cs#14.customer#20

bc#0.bs#1.f#2.fa#8.mi#9.b#10.cs#14.customer#15

bc#0.bs#1.f#2.fa#8.mi#9.b#10.cs#14.customer#20