XQuery Update

XQuery Update Facility is a small extention of XQuery for updating an XML document. Let us work on the following simple document:


<person born="23/06/1912" died="07/06/1954">
   <name>
      <first>Alan</first>
      <last>Turing</last>
   </name>
   <profession>computer scientist</profession>
   <profession>mathematician</profession>
   <profession>cryptographer</profession>
</person>

We perform the following update operations:

Delete

Remove all profession elements

delete node //profession

<person born="23/06/1912" died="07/06/1954">
  <name>
    <first>Alan</first>
    <last>Turing</last>
  </name>
</person>

Insert

Insert a profession node into the person node

insert node <profession/> into /person

<person born="23/06/1912" died="07/06/1954">
  <name>
    <first>Alan</first>
    <last>Turing</last>
  </name>
  <profession/>
</person>

Insert a text node into the profession node

insert node "computer scientist" into /person/profession

<person born="23/06/1912" died="07/06/1954">
  <name>
    <first>Alan</first>
    <last>Turing</last>
  </name>
  <profession>computer scientist</profession>
</person>

Insert two attribute nodes into the profession node

insert node (attribute start {1936}, attribute end {1954}) into /person/profession

<person born="23/06/1912" died="07/06/1954">
  <name>
    <first>Alan</first>
    <last>Turing</last>
  </name>
  <profession start="1936" end="1954">computer scientist</profession>
</person>

Insert a profession node as first node into the person node

insert node <profession/> as first into /person

<person born="23/06/1912" died="07/06/1954">
  <profession/>
  <name>
    <first>Alan</first>
    <last>Turing</last>
  </name>
  <profession start="1936" end="1954">computer scientist</profession>
</person>

Use as last (the default) to insert the node as last element into a node.

Insert a profession node before the name node

insert node <profession/> before /person/name

<person born="23/06/1912" died="07/06/1954">
  <profession/>
  <profession/>
  <name>
    <first>Alan</first>
    <last>Turing</last>
  </name>
  <profession start="1936" end="1954">computer scientist</profession>
</person>

Use after to insert the node after another node.

Sequence of updates are embedded into transactions: they are performed atomically (commit or rollback) and in parallel (not sequentially). Try this sequence of two updates (the second is illegal, and the entire transaction is rolled back):

(insert node attribute nato {1936} into /person, insert node attribute died {1954} into /person)

Try this:

let $att := /person/attribute::born return (insert node <born>{string($att)}</born> as first into $att/.., delete node $att)
```
<person died="07/06/1954">
  <born>23/06/1912</born>
  <profession/>
  <profession/>
  <name>
    <first>Alan</first>
    <last>Turing</last>
  </name>
  <profession start="1936" end="1954">computer scientist</profession>
</person>
```
Now try this:

let $att := /person/attribute::died return (delete node $att, insert node <died>{string($att)}</died> as first into $att/..)
```
<person>
  <died>07/06/1954</died>
  <born>23/06/1912</born>
  <profession/>
  <profession/>
  <name>
    <first>Alan</first>
    <last>Turing</last>
  </name>
  <profession start="1936" end="1954">computer scientist</profession>
</person>
```

Replace

Replace node name with another node

replace node //name with <name>Alan Turing</name>

<person>
  <died>07/06/1954</died>
  <born>23/06/1912</born>
  <profession/>
  <profession/>
  <name>Alan Turing</name>
  <profession start="1936" end="1954">computer scientist</profession>
</person>

Replace node value of name with another value

replace value of node //name with "A. Turing"

<person>
  <died>07/06/1954</died>
  <born>23/06/1912</born>
  <profession/>
  <profession/>
  <name>A. Turing</name>
  <profession start="1936" end="1954">computer scientist</profession>
</person>

Rename

Rename node name with another name

rename node //name as "full-name"

<person>
  <died>07/06/1954</died>
  <born>23/06/1912</born>
  <profession/>
  <profession/>
  <full-name>A. Turing</full-name>
  <profession start="1936" end="1954">computer scientist</profession>
</person>