Data Transformation Engine Database Interface Designer Reference Guide

Chapter 6 - Updating Database Tables Example Using Update Columns
Database Interface Designer Reference Guide
107
After the table is updated, it looks like this:
Please note the following:
♦ If more than one column is designated as a key column, the values generated
by a map must match the values in each designated key column for the row to
be updated.
♦ If your map generates a row with key column values that match more than one
existing record, all of the matching records in the columns you have specified
as update columns are updated with the new row values.
♦ If your map produces multiple rows with the same values for the key columns,
you lose any updates that are made as a result of all but the last row. The
updates produced by each row are overwritten by the updates from
subsequent rows with the same key values.
Example Using Update Columns
When only some columns in a table are specified as columns to be updated, the
values corresponding to all other columns are ignored when the update statement
is built and executed. For any row produced by the map, if the values for the
update key columns do not match any of the existing rows in the table or view,
the values of all columns will be inserted in the new row.