User`s guide

CHAPTER 6 Components
User’s Guide 103
Use Key Value
If Use Key Value is activated, the key value will be assigned to the value
attribute instead of the default, if the lookup does not find a match.
Lookup Empty/Null Keys
If activated, the lookup will also be performed for empty or NULL key values;
otherwise, the selected default method applies.
Lookup Size
Enter the estimated number of lookup records to optimize memory allocation
and lookup performance.
The entire result set is loaded into cache memory and remains unchanged until
the transformation process finishes. Choosing an appropriate value for Lookup
Size allows allocating memory in one piece while a low value will cause the
program to allocate memory incrementally.
For example, assume that you want to replace the product number used for
German products by the product number used in the U.S. The German products
are in the table
PRODUKTE(PR_NUMMER, PR_NAME, PR_PREIS). The IN-
Port of the DB Lookup component contains those three attributes.
The table to perform the lookup of the U.S. product number is table
LOOKUP_PRODUCTS(SOURCE, DESTINATION). The SOURCE column
contains the German product numbers and the DESTINATION column
contains the U.S. product number.
If no value for the German PR_NUMMER can be found in the
LOOKUP_PRODUCTS, the current PR_NUMMER will be replaced by the string
“INVALID”. A successful lookup will replace the German product number by
the corresponding U.S. number.
To set up the DB Lookup Component for this example, choose:
• Key Attribute:
IN.PR_NUMMER
• Value Attribute: IN.PR_NUMMER
• Default Value: “INVALID”
•Query:
SELECT SOURCE, DESTINATION FROM LOOKUP_PRODUCTS
Refer to “Entering database connection parameters” on page 71 for more
information on the previous and the following properties:
• Database