SQL/XML
SQL/XML or XML-Related Specifications is part 14 of the Structured Query Language (SQL) specification. In addition to the traditional predefined SQL data types like NUMERIC, CHAR, TIMESTAMP, ... it introduces the predefined data type XML together with constructors, several routines, functions, and XML-to-SQL data type mappings to support manipulation and storage of XML in a SQL database.
- SQL:2003-14 defines the basic datatype, mappings, predicates and functions.
- SQL:2006-14, SQL:2008-14 and SQL:2011-14 expands the older versions and approaches to XQuery.[1]
Specification
The specification defines the data type XML, functions for working with XML, including element construction, mapping data from relational tables, combining XML fragments, and embedding XQuery expressions in SQL statements. Functions which can be embedded include XMLQUERY (which extracts XML or values from an XML field) and XMLEXISTS (which predicates whether an XQuery expression is matched).
Further information and examples of the SQL/XML functions are provided in the external links below[2][3][4].
Standard compliance
The result of Wagner's objective evaluation of the SQL/XML:2006 standard compliance of Oracle 11g Release 1, MS SQL Server 2008 and MySQL 5.1.30 is shown in the following table[2], to which the data for PostgreSQL 9.1,[5][6] and IBM DB2 has been added:
| Oracle 11g Release 1 | IBM DB2 9.7 | MS SQL Server 2008 | MySQL 5.1.30 | PostgreSQL 9.1 | |
|---|---|---|---|---|---|
| Datatype XML | partial (Oracle entitles the data type 'XMLType' instead of 'XML') | High | High | No | Partial |
| SQL/XML predicates | High | High | Partial | No | Partial |
| SQL/XML functions | High | High | Partial | Low | High |
NOTE: only Oracle, IBM DB2 and MS-SQL-Server have been augmented with XQuery.
Examples
The sample SQLXML query below has SQLXML type as output(tested on DB2 9.7 and Oracle 11g):
SELECT XMLELEMENT(NAMEs "PhoneBook", -- root element name
XMLAGG( -- aggregation over the rows
XMLELEMENT(NAME "Contact",
XMLATTRIBUTES(cust.FIRST_NAME AS "Name",
cust.TEL)
)
)
)
FROM TMP.CUSTOMER AS cust;
And the output:
<PhoneBook>
<Contact Name="Daniel" TEL="788255855"/>
<Contact Name="Martin" TEL="889665447"/>
<Contact Name="Eva" TEL="111222333"/>
<Contact Name="Alena" TEL="444555666"/>
<Contact Name="Oliver" TEL="777888999"/>
<Contact Name="George" TEL="444882446"/>
<Contact Name="Jamie" TEL="123456789"/>
</PhoneBook>
Samples are taken from javalobby article[7].
References
- Funderburk, J. E.; Malaika, S.; Reinwald, B. (2002), "XML programming with SQL/XML and XQuery" (PDF), IBM Systems Journal, 41 (4): 642–665, doi:10.1147/sj.414.0642, retrieved 14 November 2011
- Wagner, Michael (2010), "1. Auflage", SQL/XML:2006 - Evaluierung der Standardkonformität ausgewählter Datenbanksysteme, Diplomica Verlag, ISBN 978-3-8366-9609-8
- Eisenberg, Andrew; Melton, Jim (2004), "Advancements in SQL/XML" (PDF), SIGMOD Record, 33 (3): 79, doi:10.1145/1031570.1031588, retrieved 14 November 2011
- Eisenberg, Andrew; Melton, Jim (2002), "SQL/XML is Making Good Progress" (PDF), SIGMOD Record, 31 (2): 101, CiteSeerX 10.1.1.109.4867, doi:10.1145/565117.565141, retrieved 14 November 2011
- PostgreSQL Conformance with ISO 9075-14 (SQL/XML), at PostgreSQL 9.1 documentation.
- PostgreSQL 9.1 XML functions, at PostgreSQL 9.1 documentation.
- Kec, Daniel (2013), SQLX - From DB Straight to XML and Back, Javalobby.org