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Alternatively, one can use the XQuery function that extracts the year from

a date as in the following query:

document("healthstudy.xml")
//Interview[year-from-dateTime(@Date)=2000 and @BMI>30]
ANSWER TO
EXERCISE8.2
First find the insulin gene locus. Then within this locus find all literature
entries. An entry is a literature reference if the reference element containing
the entry is named “Literature references.” Note the use of “..”toobtain
the name attribute of the parent element of the entry.

for $locus in document("bio.xml")//locus
where $locus/gene/@name = "Insulin gene"
return (for $entry in $locus/reference/db_entry
where $entry/../@name = "Literature references"
return $entry)
ANSWER TO
EXERCISE8.3
Look for all citations that have a MeSH heading satisfying the criteria. The
following query looks at all citations, and then within each citation it looks
at every heading. Whenever a heading satisfies the criteria, the citation is
returned.

for $citation in

document("pubmed.xml")//MedlineCitation,

$heading in

$citation//MeshHeading

where $heading/DescriptorName/@MajorTopicYN="Y"

and $heading/DescriptorName="Glutethimide"

and $heading/QualifierName="therapeutic use"

return $citation

In the query above, if a citation has more than one MeSH heading that

satisfies the criteria, then the citation will be returned more than once. One

can avoid this problem by using a “nested” subquery as in the following

query. For each citation, this query runs a separate subsidiary query that

finds all headings within the citation that satisfy the criteria. If the nested

subquery has one or more results, then the citation is returned.