Table alteration

You can alter the structure or column definitions of a table by adding columns, changing various column attributes, or deleting columns.

Table alterations and view dependencies

Before altering a table, you may want to determine whether there are views dependent on a table, by using the sa_dependent_views system procedure.

If you are altering the schema of a table with dependent views, there may be additional steps to take depending upon the type of view:

Dependent regular views When you alter the schema of a table, the definition for the table in the database is updated. If there are dependent regular views, the database server automatically recompiles them after you perform the table alteration. If the database server cannot recompile a dependent regular view after making a schema change to a table, it is likely because the change you made invalidated the view definition. In this case, you must correct the view definition.
Dependent materialized views If there are dependent materialized views, you must disable them before making the table alteration, and then re-enable them after making the table alteration. If you cannot re-enable a dependent materialized view after making a schema change to a table, it is likely because the change you made invalidated the materialized view definition. In this case, you must drop the materialized view and then create it again with a valid definition, or make suitable alterations to the underlying table before trying to re-enable the materialized view.

Changes to table ownership

You can change the owner of a table using the ALTER TABLE statement or Sybase Central. When changing the table owner, you can specify whether or not to preserve existing foreign keys within the table as well as those referring to the table. Dropping all foreign keys isolates the table, but provides increased security if needed. You can also specify whether or not to preserve existing explicitly-granted privileges. For security purposes, you can drop all explicitly-granted privileges that allow a user access to the table. Implicitly-granted privileges given to the owner of the table are given to the new owner and dropped from the old owner.