Articles & Tutorial for OCA DBA 9i certification
All articles for OCA DBA 9i certification
Tips and How Tos for OCA DBA 9i certification
How is a constraint disabled?
in OCA DBA 9i
A constraint is disabled using the DISABLE clause of the ALTER TABLE statement. When disabling a constraint, the VALIDATE or NOVALIDATE keyword can be used with the DISABLE clause.
The VALIDATE keyword specifies that the constraint is disabled and all indexes used to enforce the constraint are...
continue reading "How is a constraint disabled?" »
How is a constraint enabled?
in OCA DBA 9i
A constraint is enabled using the ENABLE clause of the ALTER TABLE statement. When enabling a constraint, the VALIDATE or NOVALIDATE keyword can be used with the ENABLE clause.
The VALIDATE keyword specifies that all existing rows in the table and new rows inserted in the table must comply...
continue reading "How is a constraint enabled?" »
How is a tablespace taken offline and online?
in OCA DBA 9i
The ALTER TABLESPACE TablespaceName OFFLINE; statement is used to take a tablespace offline. When a tablespace is taken offline, all associated data files are also taken offline. Taking a database's tablespace offline makes the tablespace unavailable for general use, while the rest of the...
continue reading "How is a tablespace taken offline and online?" »
How is an index's usage monitored?
in OCA DBA 9i
The V dynamic performance view displays statistics about index usage. It can be used to determine whether or not an index is used during database transactions. If it is found that the index is not used, it can be dropped. Dropping unused indexes eliminates unnecessary overhead and consequently...
continue reading "How is an index's usage monitored?" »
How is an Oracle database opened?
in OCA DBA 9i
The STARTUP command is used to open an Oracle database. Only a database administrator can open an Oracle database. An Oracle database is opened in three stages. First, an Oracle instance is started. Then, the instance mounts the specified database. Finally, the database is opened.
When...
continue reading "How is an Oracle database opened?" »
How is an Oracle database shut down?
in OCA DBA 9i
The SHUTDOWN command is used to shut down an Oracle database. Only a database administrator can shut down an Oracle database. An Oracle database is shut down in three stages. First, the database is closed. Then, the database is unmounted. Finally, the associated Oracle instance is shut down....
continue reading "How is an Oracle database shut down?" »
How is top-n analysis performed?
in OCA DBA 9i
Top-n analysis is performed using a top-n analysis query. Following is the structure of a top-n analysis query:
SELECT [column_list], ROWNUM
FROM (SELECT [column_list] FROM table
ORDER BY top-n_column)
WHERE ROWNUM <= n;
A top-n analysis query comprises the following elements:
A...
continue reading "How is top-n analysis performed?" »
How many types of indexes can be created?
in OCA DBA 9i
Two types of indexes can be created. They are as follows:
Unique index: Oracle automatically creates this index when a column, in a table, is defined as a PRIMARY KEY or UNIQUE constraint.
Non-unique index: This index can be created by the user.
continue reading "How many types of indexes can be created?" »
Skills required for Oracle 1Z0-007 test.
in OCA DBA 9i
Oracle has specified more than forty objectives for 1Z0-007 (Introduction to Oracle9i: SQL) test, which are covered under thirteen topics. Following are some important areas over which one should have good command before taking the test:
Executing a basic SELECT statement.
Limiting the...
continue reading "Skills required for Oracle 1Z0-007 test." »
Skills required for Oracle test 1Z0-001.
in OCA DBA 9i
Oracle has specified more than twenty objectives for 1Z0-001 (Introduction to Oracle: SQL and PL/SQL) test. Following are some important areas over which one should have good command before taking the test:
Overview of relational databases, SQL, and PL/SQL.
Writing basic SQL statements....
continue reading "Skills required for Oracle test 1Z0-001." »
