Wednesday, November 14, 2007

Oracle Job Interview Questions Part-5

How do you trap the error in forms 3.0 ?
using On-Message or On-Error triggers.

How many pages you can in a single form ?

While specifying master/detail relationship between two blocks specifying the join condition is a must ?
True or False. ?

EXIT_FORM is a restricted package procedure ?
a. True b. False

What is the usage of an ON-INSERT,ON-DELETE and ON-UPDATE TRIGGERS ?
These triggers are executes when inserting, deleting and updating operations are performed and can be used to change the default function of insert, delete or update respectively. For Eg, instead of inserting a row in a table an existing row can be updated in the same table.

What are the types of Pop-up window ?
the pop-up field editor
pop-up list of values
pop-up pages.
Alert :

What is an SQL *FORMS ?
SQL *forms is 4GL tool for developing and executing; Oracle based interactive application.

How do you control the constraints in forms ?
Select the use constraint property is ON Block definition screen.

What is the difference between restricted and unrestricted package procedure ?
Restricted package procedure that affects the basic functions of SQL * Forms. It cannot used in all triggers except key triggers. Unrestricted package procedure that does not interfere with the basic functions of SQL * Forms it can be used in any triggers.

A query fetched 10 records How many times does a PRE-QUERY Trigger and POST-QUERY Trigger will get executed ?
PRE-QUERY fires once.
POST-QUERY fires 10 times.

Give the sequence in which triggers fired during insert operations, when the following 3 triggers are defined at the same block level ?

State the order in which these triggers are executed ?

What the PAUSE package procedure does ?
Pause suspends processing until the operator presses a function key

What do you mean by a page ?
Pages are collection of display information, such as constant text and graphics

What are the type of User Exits ?
ORACLE Precompliers user exits
OCI (ORACLE Call Interface)
Non-ORACEL user exits.
Page :

What is the difference between an ON-VALIDATE-FIELD trigger and a trigger ?
On-validate-field trigger fires, when the field Validation status New or changed. Post-field-trigger whenever the control leaving form the field, it will fire.

Can we use a restricted package procedure in ON-VALIDATE-FIELD Trigger ?

Is a Key startup trigger fires as result of a operator pressing a key explicitly ?

Can we use GO-BLOCK package in a pre-field trigger ?

Can we create two blocks with the same name in form 3.0 ?

What does an on-clear-block Trigger fire?
It fires just before SQL * forms the current block.

Name the two files that are created when you generate the form give the filex extension ?
INP (Source File)
FRM (Executable File)

What package procedure used for invoke sql *plus from sql *forms ?
Host (E.g. Host (sqlplus))

What is the significance of PAGE 0 in forms 3.0 ?
Hide the fields for internal calculation.

What are the different types of key triggers ?
Function Key

What is the difference between a Function Key Trigger and Key Function Trigger ?
Function key triggers are associated with individual SQL*FORMS function keys You can attach Key function triggers to 10 keys or key sequences that normally do not perform any SQL * FORMS operations. These keys referred as key F0 through key F9.

Committed block sometimes refer to a BASE TABLE ?

Error_Code is a package proecdure ?
a. True b. false

When is cost based optimization triggered? (for DBA)

It's important to have statistics on all tables for the CBO (Cost Based Optimizer) to work correctly. If one table involved in a statement does not have statistics, Oracle has to revert to rule-based optimization for that statement. So you really want for all tables to have statistics right away; it won't help much to just have the larger tables analyzed.
Generally, the CBO can change the execution plan when you:
1. Change statistics of objects by doing an ANALYZE;
2. Change some initialization parameters (for example: hash_join_enabled, sort_area_size, db_file_multiblock_read_count).

How can one optimize %XYZ% queries? (for DBA)
It is possible to improve %XYZ% queries by forcing the optimizer to scan all the entries from the index instead of the table. This can be done by specifying hints. If the index is physically smaller than the table (which is usually the case) it will take less time to scan the entire index than to scan the entire table.

What Enter package procedure does ?
Enter Validate-data in the current validation unit.

Where can one find I/O statistics per table? (for DBA)
The UTLESTAT report shows I/O per tablespace but one cannot see what tables in the tablespace has the most I/O. The $ORACLE_HOME/rdbms/admin/catio.sql script creates a sample_io procedure and table to gather the required information. After executing the procedure, one can do a simple SELECT * FROM io_per_object; to extract the required information. For more details, look at the header comments in the $ORACLE_HOME/rdbms/admin/catio.sql script.

My query was fine last week and now it is slow. Why? (for DBA)
The likely cause of this is because the execution plan has changed. Generate a current explain plan of the offending query and compare it to a previous one that was taken when the query was performing well. Usually the previous plan is not available.
Some factors that can cause a plan to change are:
. Which tables are currently analyzed? Were they previously analyzed? (ie. Was the query using RBO and now CBO?)
. Has OPTIMIZER_MODE been changed in INIT.ORA?
. Has the DEGREE of parallelism been defined/changed on any table?
. Have the tables been re-analyzed? Were the tables analyzed using estimate or compute? If estimate, what percentage was used?
. Have the statistics changed?
. Has the INIT.ORA parameter DB_FILE_MULTIBLOCK_READ_COUNT been changed?
. Has the INIT.ORA parameter SORT_AREA_SIZE been changed?
. Have any other INIT.ORA parameters been changed?
. What do you think the plan should be? Run the query with hints to see if this produces the required performance.

Why is Oracle not using the damn index? (for DBA)
This problem normally only arises when the query plan is being generated by the Cost Based Optimizer. The usual cause is because the CBO calculates that executing a Full Table Scan would be faster than accessing the table via the index.
Fundamental things that can be checked are:
. USER_TAB_COLUMNS.NUM_DISTINCT - This column defines the number of distinct values the column holds.
. USER_TABLES.NUM_ROWS - If NUM_DISTINCT = NUM_ROWS then using an index would be preferable to doing a FULL TABLE SCAN. As the NUM_DISTINCT decreases, the cost of using an index increase thereby is making the index less desirable.
. USER_INDEXES.CLUSTERING_FACTOR - This defines how ordered the rows are in the index. If CLUSTERING_FACTOR approaches the number of blocks in the table, the rows are ordered. If it approaches the number of rows in the table, the rows are randomly ordered. In such a case, it is unlikely that index entries in the same leaf block will point to rows in the same data blocks.
. Decrease the INIT.ORA parameter DB_FILE_MULTIBLOCK_READ_COUNT - A higher value will make the cost of a FULL TABLE SCAN cheaper.
. Remember that you MUST supply the leading column of an index, for the index to be used (unless you use a FAST FULL SCAN or SKIP SCANNING).
. There are many other factors that affect the cost, but sometimes the above can help to show why an index is not being used by the CBO. If from checking the above you still feel that the query should be using an index, try specifying an index hint. Obtain an explain plan of the query either using TKPROF with TIMED_STATISTICS, so that one can see the CPU utilization, or with AUTOTRACE to see the statistics. Compare this to the explain plan when not using an index.

When should one rebuild an index? (for DBA)

You can run the 'ANALYZE INDEX VALIDATE STRUCTURE' command on the affected indexes - each invocation of this command creates a single row in the INDEX_STATS view. This row is overwritten by the next ANALYZE INDEX command, so copy the contents of the view into a local table after each ANALYZE. The 'badness' of the index can then be judged by the ratio of 'DEL_LF_ROWS' to 'LF_ROWS'.

What are the unrestricted procedures used to change the popup screen position during run time ?
Resize -View

What is an Alert ?
An alert is window that appears in the middle of the screen overlaying a portion of the current display.

Deleting a page removes information about all the fields in that page ?
a. True. b. False?
a. True.

Two popup pages can appear on the screen at a time ?Two popup pages can appear on the screen at a time ?
a. True. b. False?
a. True.

Classify the restricted and unrestricted procedure from the following.
a. Call
b. User-Exit
c. Call-Query
d. Up
e. Execute-Query
f. Message
g. Exit-From
h. Post
i. Break?

a. Call - unrestricted
b. User Exit - Unrestricted
c. Call_query - Unrestricted
d. Up - Restricted
e. Execute Query - Restricted
f. Message - Restricted
g. Exit_form - Restricted
h. Post - Restricted
i. Break - Unrestricted.

What is an User Exits ?
A user exit is a subroutine which are written in programming languages using pro*C pro *Cobol , etc., that link into the SQL * forms executable.

What is a Trigger ?
A piece of logic that is executed at or triggered by a SQL *forms event.

What is a Package Procedure ?
A Package procedure is built in PL/SQL procedure.

What is the maximum size of a form ?
255 character width and 255 characters Length.

What is the difference between system.current_field and system.cursor_field ?
1. System.current_field gives name of the field.
2. System.cursor_field gives name of the field with block name.

List the system variables related in Block and Field?
1. System.block_status
2. System.current_block
3. System.current_field
4. System.current_value
5. System.cursor_block
6. System.cursor_field
7. System.field_status.

What are the different types of Package Procedure ?
1. Restricted package procedure.
2. Unrestricted package procedure.

What are the types of TRIGGERS ?
1. Navigational Triggers.
2. Transaction Triggers.

Identify package function from the following ?
1. Error-Code
2. Break
3. Call
4. Error-text
5. Form-failure
6. Form-fatal
7. Execute-query
8. Anchor View
9. Message_code?

1. Error_Code
2. Error_Text
3. Form_Failure
4. Form_Fatal
5. Message_Code

Can you attach an lov to a field at run-time? if yes, give the build-in name.?
Yes. Set_item_proprety

Is it possible to attach same library to more than one form?

Can you attach an lov to a field at design time?

List the windows event triggers available in Forms 4.0?

What are the triggers associated with the image item?
When-Image-activated(Fires when the operator double clicks on an image Items)
When-image-pressed(fires when the operator selects or deselects the image item)

What is a visual attribute?
Visual Attributes are the font, color and pattern characteristics of objects that operators see and intract with in our application.

How many maximum number of radio buttons can you assign to a radio group?
Unlimited no of radio buttons can be assigned to a radio group
How do you pass the parameters from one form to another form?
To pass one or more parameters to a called form, the calling form must perform the following steps in a trigger or user named routine execute the create_parameter_list built-in function to programmatically. Create a parameter list to execute the add parameter built-in procedure to add one or more parameters list. Execute the call_form, New_form or run_product built_in procedure and include the name or id of the parameter list to be passed to the called form.

What is a Layout Editor?
The Layout Editor is a graphical design facility for creating and arranging items and boilerplate text and graphics objects in your application's interface.

List the Types of Items?
Text item.
Chart item.
Check box.
Display item.
Image item.
List item.
Radio Group.
User Area item.

List system variables available in forms 4.0, and not available in forms 3.0?
System Date_threshold

What are the display styles of an alert?
Stop, Caution, note

What built-in is used for showing the alert during run-time?

What built-in is used for changing the properties of the window dynamically?

What are the different types of windows?
Root window, secondary window.

What is a predefined exception available in forms 4.0?
Raise form_trigger_failure

What is a radio Group?
Radio groups display a fixed no of options that are mutually Exclusive. User can select one out of n number of options.

What are the different type of a record group?
Query record group
Static record group
Non query record group

What are the menu items that oracle forms 4.0 supports?
Plain, Check,Radio, Separator, Magic

Give the equivalent term in forms 4.0 for the following. Page, Page 0?
Page - Canvas-View
Page 0 - Canvas-view null.

What triggers are associated with the radio group?
Only when-radio-changed trigger associated with radio group
Visual Attributes.

What are the triggers associated with a check box?
Only When-checkbox-activated Trigger associated with a Check box.

Can you attach an alert to a field?

Can a root window be made modal?

What is a list item?
It is a list of text elements.

List some built-in routines used to manipulate images in image_item?

Can you change the alert messages at run-time?
If yes, give the name of the built-in to change the alert messages at run-time. Yes. Set_alert_property.

What is the built-in used to get and set lov properties during run-time?
Record Group

What is the built-in routine used to count the no of rows in a group?
Get_group _row_count
System Variables

Give the Types of modules in a form?

Write the Abbreviation for the following File Extension 1. FMB 2. MMB 3. PLL?
FMB ----- Form Module Binary.
MMB ----- Menu Module Binary.
PLL ------ PL/SQL Library Module Binary.

List the built-in routine for controlling window during run-time?

List the built-in routine for controlling window during run-time?

What is the built-in function used for finding the alert?

List the editors availables in forms 4.0?
Default editor
User_defined editors
system editors.

What buil-in routines are used to display editor dynamicaly?
Edit_text item

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