Modify table behavior in a table hierarchy
After you define a table hierarchy, you cannot modify
the structure (columns) of the existing tables. However, you can modify
the behavior of tables in the hierarchy. Table 1 shows the table behavior that
you can modify in a table hierarchy and the syntax that you use to
make modifications.
Table behavior | Syntax | Considerations |
---|---|---|
Constraint definitions | ALTER TABLE | To add or drop a constraint, use the ADD CONSTRAINT or DROP CONSTRAINT clause. For more information, see Constraints on tables in a table hierarchy. |
Indexes | CREATE INDEX, ALTER INDEX | For more information, see Add indexes to tables in a table hierarchy and the CREATE INDEX and ALTER INDEX statements in the IBM® Informix® Guide to SQL: Syntax. |
Triggers | CREATE/DROP TRIGGER | You cannot drop an inherited trigger. However, you can drop a trigger from a supertable or add a trigger to a subtable to override an inherited trigger. For information about how to modify triggers on supertables and subtables, see Triggers on tables in a table hierarchy. For information about how to create a trigger, see the IBM Informix Guide to SQL: Tutorial. |
All existing subtables automatically inherit new table
behavior when you modify a supertable in the hierarchy.
Important: When you use the ALTER TABLE statement to modify
a table in a table hierarchy, you can use only the ADD CONSTRAINT,
DROP CONSTRAINT, MODIFY NEXT SIZE, and LOCK MODE clauses.