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Oracle Interview Questions and Answers
An open form can not be execute the call_form
procedure if you chain of called forms has been
initiated by another open form?
True
Explain about horizontal, Vertical tool bar canvas
views?
Tool bar canvas views are used to create tool bars for
individual windows. Horizontal tool bars are display at
the top of a window, just under its menu bar. Vertical
Tool bars are displayed along the left side of a window
What is the purpose of the product order option in the
column property sheet?
To specify the order of individual group evaluation in a
cross products.
What is the use of image_zoom built-in?
To manipulate images in image items.
How do you reference a parameter indirectly?
To indirectly reference a parameter use the NAME IN,
COPY 'built-ins to indirectly set and reference the
parameters value' Example name_in ('capital parameter my
param'), Copy ('SURESH','Parameter my_param')
What is a timer?
Timer is an "internal time clock" that you can
programmatically create to perform an action each time
the times.
What are the two phases of block coordination?
There are two phases of block coordination: the clear
phase and the population phase. During, the clear phase,
Oracle Forms navigates internally to the detail block
and flushes the obsolete detail records. During the
population phase, Oracle Forms issues a SELECT statement
to repopulate the detail block with detail records
associated with the new master record. These operations
are accomplished through the execution of triggers.
What are Most Common types of Complex master-detail
relationships?
There are three most common types of complex
master-detail relationships:
master with dependent details
master with independent details
detail with two masters
What is a text list?
The text list style list item appears as a rectangular
box which displays the fixed number of values. When the
text list contains values that can not be displayed, a
vertical scroll bar appears, allowing the operator to
view and select undisplayed values.
What is term?
The term is terminal definition file that describes the
terminal form which you are using r20run.
What is use of term?
The term file which key is correspond to which oracle
report functions.
What is pop list?
The pop list style list item appears initially as a
single field (similar to a text item field). When the
operator selects the list icon, a list of available
choices appears.
What is the maximum no of chars the parameter can store?
The maximum no of chars the parameter can store is only
valid for char parameters, which can be upto 64K. No
parameters default to 23Bytes and Date parameter default
to 7Bytes.
What are the default extensions of the files created by
library module?
The default file extensions indicate the library module
type and storage format .pll - pl/sql library module
binary
What are the Coordination Properties in a Master-Detail
relationship?
The coordination properties are
Deferred
Auto-Query
These Properties determine when the population phase of
block
coordination should occur.
How do you display console on a window ?
The console includes the status line and message line,
and is displayed at the bottom of the window to which it
is assigned.To specify that the console should be
displayed, set the console window form property to the
name of any window in the form. To include the console,
set console window to Null.
What are the different Parameter types?
Text ParametersData Parameters
State any three mouse events system variables?
System.mouse_button_pressedSystem.mouse_button_shift
What are the types of calculated columns available?
Summary, Formula, Placeholder column.
Explain about stacked canvas views?
Stacked canvas view is displayed in a window on top of,
or "stacked" on the content canvas view assigned to that
same window. Stacked canvas views obscure some part of
the underlying content canvas view, and or often shown
and hidden programmatically.
How does one do off-line database backups? (for DBA )
Shut down the database from sqlplus or server manager.
Backup all files to secondary storage (eg. tapes).
Ensure that you backup all data files, all control files
and all log files. When completed, restart your
database.
Do the following queries to get a list of all files that
needs to be backed up:
select name from sys.v_$datafile;
select member from sys.v_$logfile;
select name from sys.v_$controlfile;
Sometimes Oracle takes forever to shutdown with the
"immediate" option. As workaround to this problem,
shutdown using these commands:
alter system checkpoint;
shutdown abort
startup restrict
shutdown immediate
Note that if you database is in ARCHIVELOG mode, one can
still use archived log files to roll forward from an
off-line backup. If you cannot take your database down
for a cold (off-line) backup at a convenient time,
switch your database into ARCHIVELOG mode and perform
hot (on-line) backups.
What is the difference between SHOW_EDITOR and
EDIT_TEXTITEM?
Show editor is the generic built-in which accepts any
editor name and takes some input string and returns
modified output string. Whereas the edit_textitem
built-in needs the input focus to be in the text item
before the built-in is executed.
What are the built-ins that are used to Attach an LOV
programmatically to an item?
set_item_property
get_item_property
(by setting the LOV_NAME property)
How does one do on-line database backups? (for DBA )
Each tablespace that needs to be backed-up must be
switched into backup mode before copying the files out
to secondary storage (tapes). Look at this simple
example.
ALTER TABLESPACE xyz BEGIN BACKUP;
! cp xyfFile1 /backupDir/
ALTER TABLESPACE xyz END BACKUP;
It is better to backup tablespace for tablespace than to
put all tablespaces in backup mode. Backing them up
separately incurs less overhead. When done, remember to
backup your control files. Look at this example:
ALTER SYSTEM SWITCH LOGFILE; -- Force log switch to
update control file headers
ALTER DATABASE BACKUP CONTROLFILE TO '/backupDir/control.dbf';
NOTE: Do not run on-line backups during peak processing
periods. Oracle will write complete database blocks
instead of the normal deltas to redo log files while in
backup mode. This will lead to excessive database
archiving and even database freezes.
How does one backup a database using RMAN? (for DBA )
The biggest advantage of RMAN is that it only backup
used space in the database. Rman doesn't put tablespaces
in backup mode, saving on redo generation overhead. RMAN
will re-read database blocks until it gets a consistent
image of it. Look at this simple backup example.
rman target sys/*** nocatalog
run {
allocate channel t1 type disk;
backup
format '/app/oracle/db_backup/%d_t%t_s%s_p%p'
( database );
release channel t1;
}
Example RMAN restore:
rman target sys/*** nocatalog
run {
allocate channel t1 type disk;
# set until time 'Aug 07 2000 :51';
restore tablespace users;
recover tablespace users;
release channel t1;
}
The examples above are extremely simplistic and only
useful for illustrating basic concepts. By default
Oracle uses the database controlfiles to store
information about backups. Normally one would rather
setup a RMAN catalog database to store RMAN metadata in.
Read the Oracle Backup and Recovery Guide before
implementing any RMAN backups.
Note: RMAN cannot write image copies directly to tape.
One needs to use a third-party media manager that
integrates with RMAN to backup directly to tape.
Alternatively one can backup to disk and then manually
copy the backups to tape.
What are the different file extensions that are created
by oracle reports?
Rep file and Rdf file.
What is strip sources generate options?
Removes the source code from the library file and
generates a library files that contains only pcode. The
resulting file can be used for final deployment, but can
not be subsequently edited in the designer.ex. f45gen
module=old_lib.pll userid=scott/tiger strip_source YES
output_file
How does one put a database into ARCHIVELOG mode? (for
DBA )
The main reason for running in archivelog mode is that
one can provide 24-hour availability and guarantee
complete data recoverability. It is also necessary to
enable ARCHIVELOG mode before one can start to use
on-line database backups. To enable ARCHIVELOG mode,
simply change your database startup command script, and
bounce the database:
SQLPLUS> connect sys as sysdba
SQLPLUS> startup mount exclusive;
SQLPLUS> alter database archivelog;
SQLPLUS> archive log start;
SQLPLUS> alter database open;
NOTE1: Remember to take a baseline database backup right
after enabling archivelog mode. Without it one would not
be able to recover. Also, implement an archivelog backup
to prevent the archive log directory from filling-up.
NOTE2: ARCHIVELOG mode was introduced with Oracle V6,
and is essential for database point-in-time recovery.
Archiving can be used in combination with on-line and
off-line database backups.
NOTE3: You may want to set the following INIT.ORA
parameters when enabling ARCHIVELOG mode:
log_archive_start=TRUE, log_archive_dest=... and
log_archive_format=...
NOTE4: You can change the archive log destination of a
database on-line with the ARCHIVE LOG START TO
'directory'; statement. This statement is often used to
switch archiving between a set of directories.
NOTE5: When running Oracle Real Application Server (RAC),
you need to shut down all nodes before changing the
database to ARCHIVELOG mode.
What is the basic data structure that is required for
creating an LOV?
Record Group.
How does one backup archived log files? (for DBA )
One can backup archived log files using RMAN or any
operating system backup utility. Remember to delete
files after backing them up to prevent the archive log
directory from filling up. If the archive log directory
becomes full, your database will hang! Look at this
simple RMAN backup script:
RMAN> run {
2> allocate channel dev1 type disk;
3> backup
4> format '/app/oracle/arch_backup/log_t%t_s%s_p%p'
5> (archivelog all delete input);
6> release channel dev1;
7> }
Does Oracle write to data files in begin/hot backup
mode? (for DBA )
Oracle will stop updating file headers, but will
continue to write data to the database files even if a
tablespace is in backup mode.
In backup mode, Oracle will write out complete changed
blocks to the redo log files. Normally only deltas
(changes) are logged to the redo logs. This is done to
enable reconstruction of a block if only half of it was
backed up (split blocks). Because of this, one should
notice increased log activity and archiving during
on-line backups.
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