Getting Started with InfoSphere Data Architect

Chapter 8 – Model Mapping and Discovery 153
it to target element. You create constant mappings by right-clicking a target element in the
Mapping Group Details view, then selecting Create Constant Mapping from the menu.
• Mapping groups: Mapping groups sort mapped elements by the target table (in a relational
database) or by the element (in an XML schema). When you generate scripts for these mapping
groups, one query is generated per mapping group.
• Invalid mappings: The mapping becomes invalid when you change the properties of data
objects in the source or target model. When the mapping editor is opened, all of the mappings
are re-validated. If the source or target object is no longer valid, then the mapping is invalidated
and a red “X” will appear on the mapping line.
8.4 Adding expressions and filters to the mapping model
You can create transformation statements for each mapping that is created. The expression may be a
filter, join, sort, or a transform function on a source column to get the desired target column value. The
expression may change either the value or data type of the source column to be compatible with the
target column. These expressions are SQL fragments and appear in the DDL that you generate from the
mapping model.
Let's create a mapping transformation expression to make sure that all of the rows in the
STUDENT.FIRST_NAME column of the NEW_SDT_INFO_SYS.dbm physical data model appear in
uppercase when they are consolidated with the information in the STUDENT_INFO_SYSTEM.dbm
physical data model.
To create a transformation expression:
1. Select the mapping line between the two STUDENT.FIRST_NAME columns. The properties of
the mapping appear in the Properties view.
2. Click the Expression Builder button next to the Transformation field. The Expression Builder
window opens.
3. Select a function. In this case, you will add a function to make sure that all first names stored in
the database are stored in uppercase characters. Expand the String node and select the
UCASE(VARCHAR) – VARCHAR function.
The function appears in the Transformation expression pane.
4. Place the cursor between the parentheses, as shown in Figure 8.10.