The UPDATE statement
identifies an existing access descriptor or view descriptor that you
want to update. UPDATE is normally used to update database connection
information, such as user IDs and passwords. If your descriptor requires
many changes, it might be easier to use the CREATE statement to overwrite
the old descriptor with a new one.
Altering a DBMS table
might invalidate descriptor files that are based on the DBMS table,
or it might cause these files to be out of date. If you re-create
a table, add a new column to a table, or delete an existing column
from a table, use the UPDATE statement to modify your descriptors
so that they use the new information.
Rules that apply to
the CREATE statement also apply to the UPDATE statement. For example,
the SUBSET statement is valid only for updating view descriptors.
The following statements
are not supported when you use the UPDATE statement: ASSIGN, RESET,
SELECT, and UNIQUE.