IBM Version 5 manual SQL mapping

root_node

element_node

Employee

attribute_node	element_node	element_node
	Proj
		dept
EmpNo
EMPNO		text_node
		WORKDEPT
element_node	element_node
ProjNo	StartDate
text_node	text_node
PROJNO	EMSTDATE

			element_node
Names of columns in DB2 tables:				Name
for example, EMPNO is a column in EMPLOYEE
table in SAMPLE database
	element_node				element_node
		firstName				lastName
	text_node				text_node
		FIRSTNAME				LASTNAME

Figure 6-16 XML Collection mapping scheme

By analyzing the mapping scheme we will be able to determine whether we can compose the entire XML document with one SQL statement or not. You can use one of the two types of mapping schemes when defining a collection in the DAD file:

￿SQL mapping. SQL mapping uses SQL SELECT statement to define the DB2 tables and conditions used for composing a document from the collection.

￿RDB_node mapping. RDB_node mapping uses an XPath-based relational database node (RDB_node). The RDB_node has child elements that define the tables, columns, and conditions used to associate XML data with DB2 tables.

SQL mapping

Defining a DAD file with SQL mapping scheme allows direct mapping from relational data to XML documents through a single SQL statement and the XPath data model. When working with SQL mapping it is important to understand the following points:

￿SQL mapping scheme can be used for composition, not for decomposition.

Chapter 6. RDB and XML integration 137