To use the row-level access control feature, add the access option to the existing create rule syntax. Access rules restrict any rows that can be viewed or modified.
Access rules are similar to domain rules, which allow table owners to control the values users can insert or update on a column. The domain rule applies restrictions to added data, functioning on update and insert commands.
Access rules apply restrictions to retrieved data, enforced on select, update and delete operations. Adaptive Server enforces the access rules on all columns that are read by a query, even if the columns are not included in the select list. In other words, in a given query, Adaptive Server enforces the domain rule on the table that is updated and the access rule on all tables that are read.
For example:
insert into orders_table select * from old_orders_table
In this query, if there are domain rules on the orders_table and access rules on the old_orders_table, Adaptive Server enforces the domain rule on the orders_table, because it is updated, and the access rule on the old_orders_table, because it is read.
Using access rules is similar to using views, or using an ad hoc query with where clauses. The query is compiled and optimized after the access rules are attached, so it does not cause performance degradation. Access rules provide a virtual view of the table data, the view depending on the specific access rules bound to the columns.
Access rules can be bound to user-defined datatypes, defined with sp_addtype. Adaptive Server enforces the access rule on user tables, which frees the table owner or Database Owner from the maintenance task of binding access rules to columns in the normalized schema. For instance, you can create a user-defined type, whose base type is varchar(30), call it username, and bind an access rule to it. Adaptive Server enforces the access rule on any tables in your application that have columns of type username.
Application developers can write flexible access rules using Java and application contexts, described in “Access rules as user-defined Java functions”, and “Using the Application Context Facility”.
