Name)
from CUSTOMER_CALL_OV CCOV
where Call_Date = TRUNC(SysDate);
You can thus return CUSTOMER data from your query without directly querying the CUSTOMER
table. In this example, the Call_Date column is used as a limiting condition for the rows returned
by the query.
154 Oracle Database 11g DBA Handbook
Whether you use row objects or column objects, you can use object views to shield your
tables from the object relationships. The tables are not modified; you administer them the way
you always did. The difference is that the users can now access the rows of CUSTOMER as if they
are row objects.
From a DBA perspective, object views allow you to continue creating and supporting standard
tables and indexes while the application developers implement the advanced object-relational
features as a layer above those tables.
Security for Abstract Datatypes
The examples in the previous sections assumed that the same user owned the ADDRESS_TY
datatype and the CUSTOMER table. What if the owner of the datatype is not the table owner?
What if another user wants to create a datatype based on a datatype you have created? In the
development environment, you should establish guidelines for the ownership and use of abstract
datatypes just as you would for tables and indexes.
For example, what if the account named KAREN_SHELL owns the ADDRESS_TY datatype,
and the user of the account named CON_K tries to create a PERSON_TY datatype? I??™ll show you
the problem with type ownership, and then show you an easy solution later in this section.
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