Matakuliah
Tahun
: T0413
: 2009
Pure XML
Pertemuan 10
XML: The foundation of SOA and Web 2.0
SOA
Web 2.0
XML
Database  DB2 9
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3
What is DB2’s pureXML technology?
<employee id=“9”>
<name>John</name>
<phone> 555 1212</phone>
</employee>
XQuery
SQL
id name
9
John
phone
employee
5551212
id=901
name
John
Relational
Engine
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phone
555-1212
XML
Engine
4
What is DB2’s pureXML technology?
• Two main characteristics:
– XML is stored in parsed-hierarchical format in
the database
– DB2 has a native XML interface to the engine
• The storage format = the processing
format
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5
Native XML Storage
• XML stored in parsed hierarchical format
create table dept (deptID char(8),…, deptdoc xml);
• Relational columns
are stored in relational
format (tables)
• XML columns are
stored natively
• XML stored in UTF8
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6
Integration: Relational and hierarchical data
PATIENTS table
NAME
SEX
AGE
Elizabeth
F
65
COFFEE SMOKE
35
DNA
15
geneX = 987
Raul
M
47
10
0
geneX = 987
…
Tina
F
58
4
10
geneX = 123
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7
SQL with Xquery/XPath
SELECT name from PATIENTS
WHERE
xmlexists('$p/Patient/MedicalDetail[geneX="987"]'
passing PATIENTS.DNA as "p")
and sex = 'F'
and age > 55
and coffee > 15
and smoke > 10
;
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8
pureXML: No need to remap for Data
Exchange
Company Data
Company Data
Edge
Relational
And XML DB
Applications
XML
Processing
Edge
Applications
XML Exchange Formats: XML
Web Services
Processing
Syndication
Industry Formats
Relational
And XML DB
Storing and querying XML without needing to re-map exchange data to relational format
Providing common integrity, recovery, security, management interfaces and mechanisms
Providing flexibility in the face of schema evolution
Supporting easy access through Web Services and Web 2.0
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9
Table definitions with XML columns
create table items (
id
int primary key not null,
brandname
varchar(30),
itemname
varchar(30),
sku
int,
srp
decimal(7,2),
comments
xml
);
create table clients(
id
int primary key not null,
name
varchar(50),
status
varchar(10),
contact
xml
);
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10
Insert & Import of XML data
INSERT INTO clients VALUES (77, 'John Smith', 'Gold', '<addr>111
Main St., Dallas, TX, 00112</addr>') ;
IMPORT from "C:\DB2workshop\Quicklabs\quicklab14a\clients.del" of
del
xml from
"C:\DB2workshop\Quicklabs\quicklab14a" INSERT INTO CLIENTS
(ID, NAME, STATUS, CONTACT);
IMPORT from "C:\DB2workshop\Quicklabs\quicklab14a\items.del" of
del
xml from
"C:\DB2workshop\Quicklabs\quicklab14a"
INSERT INTO ITEMS (ID, BRANDNAME, ITEMNAME, SKU, SRP,
COMMENTS);
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XPath
/
/dept
/dept/employee
/dept/employee/@id
/dept/employee/name
/dept/employee/phone
/dept/employee/office
(...)
XML Query Language
 Subset of XQuery & SQL/XML

<dept bldg=“101”>
<employee id=“901”>
<name>John Doe</name>
<phone>408 555 1212</phone>
<office>344</office>
</employee>
<employee id=“902”>
<name>Peter Pan</name>
<phone>408 555 9918</phone>
<office>216</office>
</employee>
employee
</dept>
id=901
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name
John Doe
phone
408-555-1212
Each node has a path
dept
employee
office
344
id=902
name
Peter Pan
phone
408-555-9918
office
216 12
XPath: Simple XPath Expressions
Use fully qualified paths to specify elements/attributes
 “@” is used to specify an attribute
 use “text()” to specify the text node under an element

<dept bldg=“101”>
<employee id=“901”>
<name>John Doe</name>
<phone>408 555 1212</phone>
<office>344</office>
</employee>
<employee id=“902”>
<name>Peter Pan</name>
<phone>408 555 9918</phone>
<office>216</office>
</employee>
</dept>
XPath
Result
/dept/@bldg
101
/dept/employee/@id
901
902
/dept/employee/name
<name>Peter Pan</name>
<name>John Doe</name>
/dept/employee/name/text()
Peter Pan
John Doe
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<dept bldg=“101”>
<employee id=“901”>
<name>John Doe</name>
<phone>408 555 1212</phone>
<office>344</office>
</employee>
<employee id=“902”>
<name>Peter Pan</name>
<phone>408 555 9918</phone>
<office>216</office>
</employee>
</dept>
XPath: Wildcards
*

matches any tag name
// is the “descendent-or-self” wildcard
XPath
Result
/dept/employee/*/text()
John Doe
408 555 1212
344
Peter Pan
408 555 9918
216
/dept/*/@id
901
902
//name/text()
Peter Pan
John Doe
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/dept//phone
<phone>408 555 1212</phone>
<phone>408 555 9918</phone>
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XPath:Predicates
Predicates are enclosed in square brackets […]
 Can have multiple predicates in one XPath
 Positional predicates: [n] selects the n-th child

<dept bldg=“101”>
<employee id=“901”>
<name>John Doe</name>
<phone>408 555 1212</phone>
<office>344</office>
</employee>
<employee id=“902”>
<name>Peter Pan</name>
<phone>408 555 9918</phone>
<office>216</office>
</employee>
</dept>
XPath
Result
/dept/employee[@id=“902”]/name
<name>Peter Pan</name>
/dept[@bldg=“101”]/employee[office >“300”]/name
<name>John Doe</name>
//employee[office=“344” OR office=“216”]/@id
901
902
/dept/employee[2]/@id
902
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<dept bldg=“101”>
<employee id=“901”>
<name>John Doe</name>
<phone>408 555 1212</phone>
<office>344</office>
</employee>
<employee id=“902”>
<name>Peter Pan</name>
<phone>408 555 9918</phone>
<office>216</office>
</employee>
</dept>
XPath: The Parent Axis
 Current
 Parent
context: “.”
context: “..”
XPath
Result
/dept/employee/name[../@id=“902”]
<name>Peter Pan</name>
/dept/employee/office[.>“300”]
<office>344</office>
/dept/employee[office > “300”]/office
<office>344</office>
/dept/employee[name=“John Doe”]/../@bldg
101
/dept/employee/name[.=“John Doe”]/../../@bldg
101
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XQuery
• XQuery supports path expressions to navigate
XML hierarchical structure
• XQuery supports both typed and untyped data
• XQuery lacks null values because XML
documents omit missing or unknown data
• XQuery returns sequences of XML data
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XQuery: The FLWOR Expression
•
•
•
•
•
FOR: iterates through a sequence, bind variable to items
LET: binds a variable to a sequence
WHERE: eliminates items of the iteration
ORDER: reorders items of the iteration
RETURN: constructs query results
create table dept(deptID char(8),deptdoc xml);
xquery
for $d in db2-fn:xmlcolumn(‘DEPT.DEPTDOC')/dept
let $emp := $d//employee/name
where $d/@bldg > 95
order by $d/@bldg
return
<EmpList>
{$d/@bldg, $emp}
</EmpList>
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Input:
<dept bldg=“101”>
<employee id=“901”>
<name>John Doe</name>
<phone>408 555 1212</phone>
<office>344</office>
</employee>
<employee id=“902”>
<name>Peter Pan</name>
<phone>408 555 9918</phone>
<office>216</office>
</employee>
</dept>
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SQL/XML queries
•
•
•
SQL/XML is designed to bridge between the SQL and XML worlds.
– Part of the SQL standard includes specifications for embedding
XQuery or XPath expressions within SQL statements
XPATH is a language for navigating XML documents to find elements or
attributes
XQuery includes support for XPATH
xmlexists function
• Restricts results based on an XML element value
• Syntax required prior to DB2 9.5: • New syntax allowed with DB2 9.5:
select name from clients
where
xmlexists('$c/Client/Address[z
ip="95116"]'
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passing CLIENTS.CONTACT
as "c")
select name from clients
where
xmlexists('$CONTACT/Client/Add
ress[zip="95116"]')
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Case sensitivity - Caution!
SQL is not case sensitive
XPath and XQuery are case sensitive!
DB2 objects (tables/columns) need to be put in upper case.
Example:
select name from clients
where
xmlexists('$contact/Client/Address[zip="95116"]')
select name from clients
where
xmlexists('$CONTACT/Client/Address[zip="95116"]')
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Curly quotes - Caution!
SQL, XPath and XQuery use straight quotes (for either single or
double quotes depending the situation)
Examples:
‘The quotes in this example are curly, which is bad!’
'The quotes in this example are straight, which is good!'
The example below uses curly quotes, so it will fail:
xquery
db2-fn:xmlcolumn(‘CLIENTS.CONTACT’)/Client/Address[zip=“95116”]
It is typical to see this problem when copy/pasting from a Word or
Powerpoint document
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xmlquery function
• Retrieve one or more element values from
our XML document
select xmlquery('$CONTACT/Client/email')
from clients
where status = 'Gold'
Retrieving XML data using “for” and “return” clauses of XQuery
SELECT name,
xmlquery ('for $e in $CONTACT/Client/email[1] return $e')
FROM clients
WHERE status = 'Gold'
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Retrieving and transforming XML into HTML
SELECT
xmlquery('for $e in $CONTACT/Client/email[1]/text()
return <p>{$e}</p>')
FROM clients
WHERE status = 'Gold'
xmltable function: From XML to Relational
select t.comment#,i.itemname,t.customerID,Message
from items i,
xmltable('$COMMENTS/Comments/Comment'
columns Comment# integer path 'CommentID',
CustomerID integer path 'CustomerID',
Message varchar(100) path 'Message') as t
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xmlelement function: From Relational to XML
select
xmlelement (name "item",itemname),
xmlelement (name "id", id),
xmlelement (name "brand",brandname),
xmlelement (name "sku",sku)
from items
where srp < 100
Review: XMLTABLE vs XMLELEMENT
XML
XMLELEMENT function
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XMLTABLE function
Relational
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Simple XQuery to return customer contact data
xquery db2-fn:xmlcolumn('CLIENTS.CONTACT')
• db2-fn:xmlcolumn is a function with a parameter that
identifies the table name and column name of an XML
column.
FLWOR expression to retrieve client fax data
xquery
for $y in db2-fn:xmlcolumn('CLIENTS.CONTACT')/Client/fax
return $y
<fax>4081112222</fax>
<fax>5559998888</fax>
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Path expression with additional filtering predicate
xquery
db2-fn:xmlcolumn('CLIENTS.CONTACT')/Client/Address[zip="95116"]
Querying DB2 XML data and returning results as HTML
xquery
<ul> {
for $y in db2-fn:xmlcolumn('CLIENTS.CONTACT')/Client/Address
order by $y/zip
return <li>{$y}</li>
}</ul>
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Sample HTML
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<ul>
<li>
<address>
<street>9407 Los Gatos Blvd.</street>
<city>Los Gatos</city>
<state>ca</state>
<zip>95302</zip>
</address>
</li>
<Address>
<street>4209 El Camino Real</street>
<city>Mountain View</city>
<state>CA</state>
<zip>95302</zip>
</address>
</li>
…
</ul>
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Embedded SQL within XQuery
• db2-fn:sqlquery
 A function which executes an SQL query and returns only the
selected data
 The SQL Query passed to db2-fn:sqlquery must return XML data
 This XML data can then be further processed by XQuery
xquery
for $y in
db2-fn:sqlquery('select comments from items where srp > 100')/Comments/Comment
where $y/ResponseRequested='Yes'
return (
<action>
{$y//ProductID}
{$y//CustomerID}
{$y//Message}
</action>
)
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Joins with SQL/XML
create table dept (unitID char(8), deptdoc xml)
create table unit (unitID char(8) primary key not null,
name
char(20),
manager varchar(20),
...
)
select u.unitID
from dept d, unit u
where XMLEXISTS ('$e//employee[name = $m] '
passing d.deptdoc as "e", u.manager as "m")
select u.unitID
from dept d, unit u
where u.manager = XMLCAST(XMLQUERY('$e//employee/name'
passing d.deptdoc as "e") as char(20))
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DELETE operations
• DELETE a row based on a condition that uses an XML element
– Simply use an SQL DELETE statements
– A DELETE first searches for the document, and then deletes it.
The search part can be done using the same SQL/XML
functions as when querying data
UPDATE operations
• With DB2 9, use:
– SQL UPDATE statement
– or Stored Procedure
• DB2XMLFUNCTIONS.XMLUPDATE
• With DB2 9.5:
– Use the TRANSFORM expression
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Update Example with DB2 9.5: TRANSFORM expression
Adding an element to the end
UPDATE purchaseorder SET porder =
xmlquery('transform
copy $po := $order
modify do insert
document { <item>
<partid>100-103-01</partid>
<name>Snow Shovel, Super Deluxe 26 inch</name>
<quantity>4</quantity>
<price>49.99</price>
</item>
}
into $po/PurchaseOrder
return $po'
passing purchaseorder.porder as "order")
where poid=5012;
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Update Example with DB2 9.5: TRANSFORM expression
Deleting an element
UPDATE purchaseorder SET porder =
xmlquery('transform
copy $po := $order
modify do delete
$po/PurchaseOrder/item[partid = ''100-201-01'']
return $po'
passing porder as "order")
WHERE poid=5012;
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XML Indexing Examples
create unique index idx1 on customer(info)
generate key using
xmlpattern '/customerinfo/@Cid'
as sql double;
create index idx2 on customer(info)
generate key using
xmlpattern '/customerinfo/name'
as sql varchar(40);
create index idx3 on customer(info)
generate key using
xmlpattern '//name'
as sql varchar(40);
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create table customer( info XML);
<customerinfo Cid="1004">
<name>Matt Foreman</name>
<addr country="Canada">
<street>1596 Baseline</street>
<city>Toronto</city>
<state>Ontario</state>
<pcode>M3Z-5H9</pcode>
</addr>
<phone type="work">905-555-4789</phone>
<phone type="home">416-555-3376</phone>
<assistant>
<name>Peter Smith</name>
<phone type="home">416-555-3426</phone>
</assistant>
</customerinfo>
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XML Indexing Examples
create table customer( info XML);
Don’t index everything!
Too expensive for
insert, update, delete !
create index idx4 on customer(info)
generate key using
xmlpattern '//text()'
as sql varchar(40);
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<customerinfo Cid="1004">
<name>Matt Foreman</name>
<addr country="Canada">
<street>1596 Baseline</street>
<city>Toronto</city>
<state>Ontario</state>
<pcode>M3Z-5H9</pcode>
</addr>
<phone type="work">905-555-4789</phone>
<phone type="home">416-555-3376</phone>
<assistant>
<name>Peter Smith</name>
<phone type="home">416-555-3426</phone>
</assistant>
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</customerinfo>
XML Schema Support
• XML Schemas are supported using “XML
Schema repositories”
• To validate based on an XML Schema you can:
– Use the XMLVALIDATE function during an INSERT
– Use a BEFORE Trigger
• To test if an XML document has been validated,
you can use the “IS VALIDATED” predicate on a
CHECK constraint
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35
What does an
XML Schema do?
DB2 pureXML Schema Flexibility
Document validation for zero, one, or many schemas per XML column:
Always Well Formed XML
(a)
(b)
(c)
(d)
No Schema
One Schema
Schema V1
& Schema V2
Documents
w/ and w/o
schema
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(e)
Any mix you want!
Most databases only support (a) and (b). DB2 9 allows (a) through (e).
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