Use of Table Tags when Updating
Not all databases support use of table tags in
UPDATE SQL statements. Each DB Access Module takes care of this internally so that
RWDBUpdater produces a
UPDATE SQL with or without table tags, depending on the module. The use of table tags by each of the Access Modules is documented in the Access Module User's Guides in the section on updaters and deleters.
Correlated updates explained in
Subqueries and Correlated Updates contain subqueries that reference the table being updated. If a particular Access Module does not support the use of table tags in
RWDBUpdater, the column name in the subquery that references the table being updated may still get qualified using the table tag. This can be prevented by clearing the tag on the table being updated, like this:
RWDBTable primary = myDbase.table("primary");
primary.tag("");
