OCP 1z0-047 Short Notes: Exam passing tips

OCP 1z0-047 Short Notes: Exam passing tips

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Retrieving data using the SQL SELECT statement and using single row functions to customize the output

• /*...*/ and -- are used to put comments in an Oracle program.


• The CREATE TABLE does not end immediately with a semicolon, and a column name cannot start with a numeric value. However, a numeric value can be used in between a column name.


• Name of a table cannot start with @ special character.


• Knowing about the GROUP BY clause.

• + (unary), - (unary), *, /, ||, =, !=, <, >, <=, >=, IS NULL, LIKE, BETWEEN, IN, NOT, AND, OR is the correct order of operators precedence.


• The ROLLBACK command is used to end the current transaction, and discard any changes made since the beginning of the transaction.

• The length of a column can be increased even if it contains data. However, the data type of the column cannot be modified if it contains any data.


• The parameters used to maximize the space in Flash Recovery Area.


• User error failure refers to a database failure that results due to certain transactions on a database by a user.


• Flashback Query is used to view and repair historical data, and to view the contents of a table at any specific point in time.


• UNDO_RETENTION is a parameter in the init.ora initialization parameters file that specifies the time period in seconds for which a system retains undo data for committed transactions.


• Once the Flashback Versions Query is run to diagnose the erroneous transaction, the Flashback Transaction Query helps in the repair process of the transaction.


• The correct order of steps that will enable the flashback database are as follows:
  1. Put the database in Archive log mode.
  2. Set up a flash recovery area.
  3. Set the period for the flashback retention target.
  4. Shut down and mount the database.
  5. Enable flashback logging.
  6. Open the database.
• The overall utilization of the flash recovery area is displayed in megabytes.


• SQL statement can be used to flashback a database.


• Take the following steps to enable the Flashback Database:
  1. Ensure that the database is in Archive Log mode.
  
  
  2. Setup a flash recovery area.
  
  
  3. Set the duration for the flashback retention target.
  
  
  4. Shutdown the database.
  
  
  5. Mount the database.
  
  
  6. Enable flashback logging.
  
  
  7. Open the database.
• The dropped table can be recovered by using Flashback Drop.


• The flashback database is enabled only in Archive log mode, as it recovers the database to an earlier specific point of time.


• Flashback Database is used to reverse the changes made to a table.


• The Perform Recovery: Review screen is used to display the RMAN script that performs the Flashback Database recovery.


• The portlist.ini file is used to get all the port numbers of the HTTP listeners.


• RVWR is a background process, which is a part of the Flashback Database Architecture.


• LGWR is a background process that is a part of Flashback Database Architecture.


• SELECT oldest_flashback_scn FROM V; is used to retrieve an approximate system change number (SCN) to which a database can be flashed back.

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