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Saturday 11 May 2013

Oracle Interview Questions and Answers 30

04:49

What third party tools can be used with Oracle EBU/ RMAN? (for DBA)
The following Media Management Software Vendors have integrated their media management software packages with Oracle Recovery Manager and Oracle7 Enterprise Backup Utility. The Media Management Vendors will provide first line technical support for the integrated backup/recover solutions.
Veritas NetBackup
EMC Data Manager (EDM)
HP OMNIBack II
IBM's Tivoli Storage Manager - formerly ADSM
Legato Networker
ManageIT Backup and Recovery
Sterling Software's SAMS:Alexandria - formerly from Spectralogic
Sun Solstice Backup

Why and when should one tune? (for DBA)
One of the biggest responsibilities of a DBA is to ensure that the Oracle database is tuned properly. The Oracle RDBMS is highly tunable and allows the database to be monitored and adjusted to increase its performance. One should do performance tuning for the following reasons:
The speed of computing might be wasting valuable human time (users waiting for response); Enable your system to keep-up with the speed business is conducted; and Optimize hardware usage to save money (companies are spending millions on hardware). Although this FAQ is not overly concerned with hardware issues, one needs to remember than you cannot tune a Buick into a Ferrari.

How can a break order be created on a column in an existing group? What are the various sub events a mouse double click event involves?
By dragging the column outside the group.

 What are object group?
An object group is a container for a group of objects. You define an object group when you want to package related objects so you can copy or reference them in another module.

What are referenced objects?
Referencing allows you to create objects that inherit their functionality and appearance from other objects. Referencing an object is similar to copying an object, except that the resulting reference object maintains a link to its source object. A reference object automatically inherits any changes that have been made to the source object when you open or regenerate the module that contains the reference object.

Can you store objects in library?
Referencing allows you to create objects that inherit their functionality and appearance from other objects. Referencing an object is similar to copying an object, except that the resulting reference object maintains a link to its source object. A reference object automatically inherits any changes that have been made to the source object when you open or regenerate the module that contains the reference object.

Is forms 4.5 object oriented tool ? why?
yes , partially. 1) PROPERTY CLASS - inheritance property 2) OVERLOADING : procedures and functions.

Can you issue DDL in forms?
yes, but you have to use FORMS_DDL.
Referencing allows you to create objects that inherit their functionality and appearance from other objects. Referencing an object is similar to copying an object, except that the resulting reference object maintains a link to its source object. A reference object automatically inherits any changes that have been made to the source object when you open or regenerate the module that contains the reference object. Any string expression up to 32K:
- a literal
- an expression or a variable representing the text of a block of dynamically created PL/SQL code
- a DML statement or
- a DDL statement
Restrictions:
The statement you pass to FORMS_DDL may not contain bind variable references in the string, but the values of bind variables can be concatenated into the string before passing the result to FORMS_DDL.

Is there a limit on the size of a PL/SQL block?
Currently, the maximum parsed/compiled size of a PL/SQL block is 64K and the maximum code size is 100K. You can run the following select statement to query the size of an existing package or procedure.
SQL> select * from dba_object_size where name = 'procedure_name'


Can one read/write files from PL/SQL?
Included in Oracle 7.3 is a UTL_FILE package that can read and write files. The directory you intend writing to has to be in your INIT.ORA file (see UTL_FILE_DIR=... parameter). Before Oracle 7.3 the only means of writing a file was to use DBMS_OUTPUT with the SQL*Plus SPOOL command.
DECLARE
fileHandler UTL_FILE.FILE_TYPE;
BEGIN
fileHandler := UTL_FILE.FOPEN('/home/oracle/tmp', 'myoutput','W');
UTL_FILE.PUTF(fileHandler, 'Value of func1 is %sn', func1(1));
UTL_FILE.FCLOSE(fileHandler);
END;


How can I protect my PL/SQL source code?
PL/SQL V2.2, available with Oracle7.2, implements a binary wrapper for PL/SQL programs to protect the source code. This is done via a standalone utility that transforms the PL/SQL source code into portable binary object code (somewhat larger than the original). This way you can distribute software without having to worry about exposing your proprietary algorithms and methods. SQL*Plus and SQL*DBA will still understand and know how to execute such scripts. Just be careful, there is no "decode" command available.
The syntax is:
wrap iname=myscript.sql oname=xxxx.yyy


Can one use dynamic SQL within PL/SQL? OR Can you use a DDL in a procedure ? How ?
From PL/SQL V2.1 one can use the DBMS_SQL package to execute dynamic SQL statements.
Eg: CREATE OR REPLACE PROCEDURE DYNSQL
AS
cur integer;
rc integer;
BEGIN
cur := DBMS_SQL.OPEN_CURSOR;
DBMS_SQL.PARSE(cur,'CREATE TABLE X (Y DATE)', DBMS_SQL.NATIVE);
rc := DBMS_SQL.EXECUTE(cur);
DBMS_SQL.CLOSE_CURSOR(cur);
END;


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