About SQL To perform many of its operations, EM Express submits structured query language (SQL) statements to the database. SQL (pronounced like sequel) is an industry-standard English-like computer programming language for querying and updating databases. The following is an example of a SQL qu...
About the Automatic SQL Tuning Advisor The SQL Tuning Advisor runs automatically during system maintenance windows (time periods) as a maintenance task. During each automatic run, the advisor selects high-load SQL queries in the system and generates recommendations on how to tune these queries. ...
About the Backup Retention Policy and the Fast Recovery Area Space management in the fast recovery area is governed by a backup retention policy. A retention policy determines when files are obsolete, meaning that they are no longer needed to m...
About the Memory Advisors Adequate physical memory has a significant impact on the performance of your Oracle Database. With its automatic memory management capabilities, Oracle Database can...
About the Oracle Suggested Backup Strategy and Retention When using the Oracle suggested backup strategy, the retention is dictated by the recovery and not by the configured retention. In order to get retention beyond 24 hours, you must change the RECOVER statement to something like: RECOVER COP...
About the SQL Tuning Advisor The SQL Tuning Advisor examines a given SQL statement or a set of SQL statements and provides recommendations to improve efficiency. It can make various types of recommendations, such as creating a SQL profile (a collection of information that enables the query optim...
About Undo Data When a transaction modifies data, Oracle Database copies the original data before modifying it. The original copy of the modified data is called undo data. Saving this information is necessary for the following reasons: ...
About User Privileges and Roles User privileges provide a basic level of database security. They are designed to control user access to data and to limit the kinds of SQL statements that users can execute. When creating a user, you grant privileges to enable the user to connect to the database, ...
About Views Views are customized presentations of data in one or more tables or other views. You can think of them as stored queries. Views do not actually contain data, but instead derive their data from the tables upon which they are based. These tables are referred to as the base tables of th...
Adding a New Table Constraint In this example, you add a table constraint to the purchase_orders table that you created in "Example: Creating a Table" on page 8-11. To enforce the rule that the po_ date_received value must be either th...
