What is difference between SQL and SQL*PLUS?

What is difference between SQL and SQL*PLUS? 

SQL*PLUS is a command line tool where as SQL and PL/SQL language interface and reporting tool. Its a command line tool that allows user to type SQL commands to be executed directly against an Oracle database. SQL is a language used to query the relational database(DML,DCL,DDL). SQL*PLUS commands are used to format query result, Set options, Edit SQL commands and PL/SQL.

What are various joins used while writing SUBQUERIES? 
Self join-Its a join foreign key of a table references the same table. Outer Join--Its a join condition used where One can query all the rows of one of the tables in the join condition even though they don't satisfy the join condition.
Equi-join--Its a join condition that retrieves rows from one or more tables in which one or more columns in one table are equal to one or more columns in the second table.

What a SELECT FOR UPDATE cursor represent.? 
SELECT......FROM......FOR......UPDATE[OF column-reference][NOWAIT]
The processing done in a fetch loop modifies the rows that have been retrieved by the cursor. A convenient way of modifying the rows is done by a method with two parts: the FOR UPDATE clause in the cursor declaration, WHERE CURRENT OF CLAUSE in an UPDATE or declaration statement.

What are various privileges that a user can grant to another user? 
-SELECT
-CONNECT
-RESOURCES

Display the records between two range? 
select rownum, empno, ename from emp where rowid in (select rowid from emp where rownum <=&upto minus select rowid from emp where rownum<&Start);

minvalue.sql Select the Nth lowest value from a table? 
select level, min('col_name') from my_table where level = '&n' connect by prior ('col_name') < 'col_name') group by level; Example: Given a table called emp with the following columns: -- id number -- name varchar2(20) -- sal number -- -- For the second lowest salary: -- select level, min(sal) from emp -- where level=2 -- connect by prior sal <>

What is difference between Rename and Alias? 
Rename is a permanent name given to a table or column whereas Alias is a temporary name given to a table or column which do not exist once the SQL statement is executed.

Difference between an implicit & an explicit cursor.? 
only one row. However,queries that return more than one row you must declare an explicit cursor or use a cursor FOR loop. Explicit cursor is a cursor in which the cursor name is explicitly assigned to a SELECT statement via the CURSOR...IS statement. An implicit cursor is used for all SQL statements Declare, Open, Fetch, Close. An explicit cursors are used to process multirow SELECT statements An implicit cursor is used to process INSERT, UPDATE, DELETE and single row SELECT. .INTO statements.

What is a OUTER JOIN? 
Outer Join--Its a join condition used where you can query all the rows of one of the tables in the join condition even though they don’t satisfy the join condition.

What is a cursor? 
Oracle uses work area to execute SQL statements and store processing information PL/SQL construct called a cursor lets you name a work area and access its stored information A cursor is a mechanism used to fetch more than one row in a Pl/SQl block.

What is the purpose of a cluster? 
Oracle does not allow a user to specifically locate tables, since that is a part of the function of the RDBMS. However, for the purpose of increasing performance, oracle allows a developer to create a CLUSTER. A CLUSTER provides a means for storing data from different tables together for faster retrieval than if the table placement were left to the RDBMS.

What is OCI. What are its uses? 
Oracle Call Interface is a method of accesing database from a 3GL program. Uses--No precompiler is required,PL/SQL blocks are executed like other DML statements.
The OCI library provides
--functions to parse SQL statemets
--bind input variables
--bind output variables
--execute statements
--fetch the results

How you open and close a cursor variable. Why it is required? 
OPEN cursor variable FOR SELECT...Statement
CLOSE cursor variable In order to associate a cursor variable with a particular SELECT statement OPEN syntax is used. In order to free the resources used for the query CLOSE statement is used.

Display Odd/ Even number of records? 
Odd number of records:
select * from emp where (rowid,1) in (select rowid, mod(rownum,2) from emp);
Output:-
1
3
5
Even number of records:
select * from emp where (rowid,0) in (select rowid, mod(rownum,2) from emp)
Output:-
2
4
6

What are various constraints used in SQL? 
-NULL
-NOT NULL
-CHECK
-DEFAULT

Can cursor variables be stored in PL/SQL tables. If yes how. If not why? 
No, a cursor variable points a row which cannot be stored in a two-dimensional PL/SQL table.

Difference between NO DATA FOUND and %NOTFOUND? 
NO DATA FOUND is an exception raised only for the SELECT....INTO statements when the where clause of the querydoes not match any rows. When the where clause of the explicit cursor does not match any rows the %NOTFOUND attribute is set to TRUE instead.

What WHERE CURRENT OF clause does in a cursor

What WHERE CURRENT OF clause does in a cursor? 
LOOP
SELECT num_credits INTO v_numcredits FROM classes
WHERE dept=123 and course=101;
UPDATE students
FHKO;;;;;;;;;SET current_credits=current_credits+v_numcredits
WHERE CURRENT OF X;

There is a string 120000 12 0 .125 , how you will find the position of the decimal place? 
INSTR('120000 12 0 .125',1,'.')
output 13

What are different modes of parameters used in functions and procedures? 
-IN -OUT -INOUT

How you were passing cursor variables in PL/SQL 2.2? 
In PL/SQL 2.2 cursor variables cannot be declared in a package.This is because the storage for a cursor variable has to be allocated using Pro*C or OCI with version 2.2, the only means of passing a cursor variable to a PL/SQL block is via bind variable or a procedure parameter.

When do you use WHERE clause and when do you use HAVING clause?

When do you use WHERE clause and when do you use HAVING clause? 

HAVING clause is used when you want to specify a condition for a group function and it is written after GROUP BY clause. The WHERE clause is used when you want to specify a condition for columns, single row functions except group functions and it is written before GROUP BY clause if it is used.

Difference between procedure and function

Difference between procedure and function.? 
Functions are named PL/SQL blocks that return a value and can be called with arguments procedure a named block that can be called with parameter. A procedure all is a PL/SQL statement by itself, while a Function call is called as part of an expression.

Which is more faster - IN or EXISTS? 
EXISTS is more faster than IN because EXISTS returns a Boolean value whereas IN returns a value.

How will you delete duplicating rows from a base table?

How will you delete duplicating rows from a base table? 

delete from table_name where rowid not in (select max(rowid) from table group by duplicate_values_field_name); or delete duplicate_values_field_name dv from table_name ta where rowid <(select min(rowid) from table_name tb where ta.dv=tb.dv);

What is syntax for dropping a procedure and a function .Are these operations possible?
Drop Procedure procedure_name
Drop Function function_name

Difference between database triggers and form triggers?

Difference between database triggers and form triggers? 

-Data base trigger(DBT) fires when a DML operation is performed on a data base table. Form trigger(FT) Fires when user presses a key or navigates between fields on the screen
-Can be row level or statement level No distinction between row level and statement level.
-Can manipulate data stored in Oracle tables via SQL Can manipulate data in Oracle tables as well as variables in forms.
-Can be fired from any session executing the triggering DML statements. Can be fired only from the form that define the trigger.
-Can cause other database triggers to fire. Can cause other database triggers to fire, but not other form triggers.

What is a cursor for loop? 

Cursor For Loop is a loop where oracle implicitly declares a loop variable, the loop index that of the same record type as the cursor's record.

What is use of a cursor variable?

What is use of a cursor variable? How it is defined? 
A cursor variable is associated with different statements at run time, which can hold different values at run time. Static cursors can only be associated with one run time query. A cursor variable is reference type (like a pointer in C).
Declaring a cursor variable:
TYPE type_name IS REF CURSOR RETURN return_type type_name is the name of the reference type,return_type is a record type indicating the types of the select list that will eventually be returned by the cursor variable.

How do you find the numbert of rows in a Table ?

How do you find the numbert of rows in a Table ? 

A bad answer is count them (SELECT COUNT(*) FROM table_name)
A good answer is :-
'By generating SQL to ANALYZE TABLE table_name COUNT STATISTICS by querying Oracle System Catalogues (e.g. USER_TABLES or ALL_TABLES).
The best answer is to refer to the utility which Oracle released which makes it unnecessary to do ANALYZE TABLE for each Table individually.

What is the maximum buffer size that can be specified using the DBMS_OUTPUT.ENABLE function? 

1,000,00

What are cursor attributes? 

-%ROWCOUNT
-%NOTFOUND
-%FOUND
-%ISOPEN

There is a % sign in one field of a column. What will be the query to find it? 

'' Should be used before '%'.

What is ON DELETE CASCADE ? 

When ON DELETE CASCADE is specified ORACLE maintains referential integrity by automatically removing dependent foreign key values if a referenced primary or unique key value is removed.

What is the fastest way of accessing a row in a table ? 

Using ROWID.CONSTRAINTS

What is difference between TRUNCATE & DELETE ? in SQL

What is difference between TRUNCATE & DELETE ?

TRUNCATE commits after deleting entire table i.e., can not be rolled back. Database triggers do not fire on TRUNCATEDELETE allows the filtered deletion. Deleted records can be rolled back or committed. Database triggers fire on DELETE.

oracle- What are the usage of SAVEPOINTS ?

What are the usage of SAVEPOINTS ?

SAVEPOINTS are used to subdivide a transaction into smaller parts. It enables rolling back part of a transaction. Maximum of five save points are allowed.

Eg -

update emp set sal=sal+100 where empid <>

savepoint a;

update emp set sal=sal+50 where empid <>

savepoint b;

update emp set sal=sal+150 where empid <>

savepoint c;

update emp set commission=0 where designation = manager;

rollback to savepoint b;

-- above statement rollbacks all statements issued after the savepoint b;

For more detailed information, please refer oracle offial site which gives much broader view of the scenario and usage.

SAVEPOINT

oracle - What is ROWID ?

What is ROWID ?
ROWID is a pseudo column attached to each row of a table. It is 18 character long, blockno, rownumber are the components of ROWID.

Explain Connect by Prior ?in a session before accessing next value ? 
Retrieves rows in hierarchical order.e.g. select empno, ename from emp where.

How many LONG columns are allowed in a table ? Is it possible to use LONG columns in WHERE clause or ORDER BY ? 
Only one LONG columns is allowed. It is not possible to use LONG column in WHERE or ORDER BY clause.

What is Referential Integrity ? 
Maintaining data integrity through a set of rules that restrict the values of one or more columns of the tables based on the values of primary key or unique key of the referenced table.

What is a join ? Explain the different Types of joins ?

What is a join ? Explain the different types of joins ? 
Join is a query which retrieves related columns or rows from multiple tables.Self Join - Joining the table with itself.Equi Join - Joining two tables by equating two common columns.Non-Equi Join - Joining two tables by equating two common columns.Outer Join - Joining two tables in such a way that query can also retrieve rows that do not have corresponding join value in the other table.

If an unique key constraint on DATE column is created, will it validate the rows that are inserted with SYSDATE ? 
It won't, Because SYSDATE format contains time attached with it.

page 20

How does one stop and start the OMS? (for DBA)
Use the following command sequence to stop and start the OMS (Oracle Management Server):
oemctl start oms
oemctl status oms sysman/oem_temp
oemctl stop oms sysman/oem_temp
Windows NT/2000 users can just stop and start the required services. The default OEM administrator is "sysman" with a password of "oem_temp".
NOTE: Use command oemctrl instead of oemctl for Oracle 8i and below.

What is an Integrity Constraint ? 
Integrity constraint is a rule that restricts values to a column in a table.

How does one create a repository? (for DBA)
For OEM v2 and above, start the Oracle Enterprise Manager Configuration Assistant (emca on Unix) to create and configure the management server and repository. Remember to setup a backup for the repository database after creating it.

If a View on a single base table is manipulated will the changes be reflected on the base table ? 
If changes are made to the tables which are base tables of a view will the changes be reference on the view.

The following describes means to create a OEM V1.x (very old!!!) repository on WindowsNT:

. Create a tablespace that would hold the repository data. A size between 200- 250 MB would be ideal. Let us call it Dummy_Space.
. Create an Oracle user who would own this repository. Assign DBA, SNMPAgent, Exp_Full_database, Imp_Full_database roles to this user. Lets call this user Dummy_user. Assign Dummy_Space as the default tablespace.
. Create an operating system user with the same name as the Oracle username. I.e. Dummy_User. Add 'Log on as a batch job' under advanced rights in User manager.
. Fire up Enterprise manager and log in as Dummy_User and enter the password. This would trigger the creation of the repository. From now on, Enterprise manager is ready to accept jobs.

What is a database link ? 
Database Link is a named path through which a remote database can be accessed.

How does one list one's databases in the OEM Console? (for DBA)

How does one list one's databases in the OEM Console? (for DBA)

Follow these steps to discover databases and other services from the OEM Console:
1. Ensure the GLOBAL_DBNAME parameter is set for all databases in your LISTENER.ORA file (optional). These names will be listed in the OEM Console. Please note that names entered are case sensitive. A portion of a listener.ora file:
(SID_DESC =
(GLOBAL_DBNAME = DB_name_for_OEM)
(SID_NAME = ...
2. Start the Oracle Intelligent Agent on the machine you want to discover. See section "How does one start the Oracle Intelligent Agent?".
3. Start the OEM Console, navigate to menu "Navigator/ Discover Nodes". The OEM Discovery Wizard will guide you through the process of discovering your databases and other services.

What is CYCLE/NO CYCLE in a Sequence ? 
CYCLE specifies that the sequence continues to generate values after reaching either maximum or minimum value. After pan ascending sequence reaches its maximum value, it generates its minimum value. After a descending sequence reaches its minimum, it generates its maximum.NO CYCLE specifies that the sequence cannot generate more values after reaching its maximum or minimum value.

What is correlated sub-query ? 
Correlated sub query is a sub query which has reference to the main query.

What are the data types allowed in a table ? 
CHAR,VARCHAR2,NUMBER,DATE,RAW,LONG and LONG RAW.

What is difference between CHAR and VARCHAR2 ? What is the maximum SIZE allowed for each type ? 
CHAR pads blank spaces to the maximum length. VARCHAR2 does not pad blank spaces. For CHAR it is 255 and 2000 for VARCHAR2.

Can a view be updated/inserted/deleted? If Yes under what conditions ? 
A View can be updated/deleted/inserted if it has only one base table if the view is based on columns from one or more tables then insert, update and delete is not possible.

What are the different types of Coordinations of the Master with the Detail block? 
POPULATE_GROUP(function)
POPULATE_GROUP_WITH_QUERY(function)
SET_GROUP_CHAR_CELL(procedure)
SET_GROUPCELL(procedure)
SET_GROUP_NUMBER_CELL(procedure)

Use the ADD_GROUP_COLUMN function to add a column to a record group that was created at design time? 
I) TRUE II) FALSE 
II) FALSE

Use the ADD_GROUP_ROW procedure to add a row to a static record group? 
I) TRUE II) FALSE 
I) FALSE

maxvalue.sql Select the Nth Highest value from a table

maxvalue.sql Select the Nth Highest value from a table? 

select level, max('col_name') from my_table where level = '&n' connect by prior ('col_name') > 'col_name')

group by level;
Example:
Given a table called emp with the following columns:
-- id number
-- name varchar2(20)
-- sal number
--
-- For the second highest salary:
-- select level, max(sal) from emp
-- where level=2
-- connect by prior sal > sal
-- group by level

Find out nth highest salary from emp table? 
SELECT DISTINCT (a.sal) FROM EMP A WHERE &N = (SELECT COUNT (DISTINCT (b.sal)) FROM EMP B WHERE a.sal<=b.sal); For E.g.:- Enter value for n: 2 SAL --------- 3700

Suppose a customer table is having different columns like customer no, payments.What will be the query to select top three max payments? 
SELECT customer_no, payments from customer C1
WHERE 3<=(SELECT COUNT(*) from customer C2 WHERE C1.payment <= C2.payment)

How you will avoid your query from using indexes? 
SELECT * FROM emp
Where emp_no+' '=12345;
i.e you have to concatenate the column name with space within codes in the where condition.
SELECT /*+ FULL(a) */ ename, emp_no from emp
where emp_no=1234;
i.e using HINTS

What utility is used to create a physical backup? 
Either rman or alter tablespace begin backup will do..

Back ground processes in Oracle

What are the Back ground processes in Oracle and what are they. 

This is one of the most frequently asked question.There are basically 9 Processes but in a general system we need to mention the first five background processes.They do the house keeping activities for the Oracle and are common in any system.
The various background processes in oracle are
a) Data Base Writer(DBWR) :: Data Base Writer Writes Modified blocks from Database buffer cache to Data Files.This is required since the data is not written whenever a transaction is committed.
b)LogWriter(LGWR) :: LogWriter writes the redo log entries to disk. Redo Log data is generated in redo log buffer of SGA. As transaction commits and log buffer fills, LGWR writes log entries into a online redo log file.
c) System Monitor(SMON) :: The System Monitor performs instance recovery at instance startup. This is useful for recovery from system failure
d)Process Monitor(PMON) :: The Process Monitor performs process recovery when user Process fails. Pmon Clears and Frees resources that process was using.
e) CheckPoint(CKPT) :: At Specified times, all modified database buffers in SGA are written to data files by DBWR at Checkpoints and Updating all data files and control files of database to indicate the most recent checkpoint
f)Archieves(ARCH) :: The Archiver copies online redo log files to archival storal when they are busy.
g) Recoveror(RECO) :: The Recoveror is used to resolve the distributed transaction in network
h) Dispatcher (Dnnn) :: The Dispatcher is useful in Multi Threaded Architecture
i) Lckn :: We can have upto 10 lock processes for inter instance locking in parallel sql.

How many types of Sql Statements are there in Oracle 
There are basically 6 types of sql statments.They are
a) Data Definition Language(DDL) :: The DDL statements define and maintain objects and drop objects.
b) Data Manipulation Language(DML) :: The DML statements manipulate database data.
c) Transaction Control Statements :: Manage change by DML
d) Session Control :: Used to control the properties of current session enabling and disabling roles and changing .e.g. :: Alter Statements, Set Role
e) System Control Statements :: Change Properties of Oracle Instance .e.g.:: Alter System
f) Embedded Sql :: Incorporate DDL, DML and T.C.S in Programming Language.e.g:: Using the Sql Statements in languages such as 'C', Open, Fetch, execute and close

What is a Transaction in Oracle ?
A transaction is a Logical unit of work that compromises one or more SQL Statements executed by a single User. According to ANSI, a transaction begins with first executable statement and ends when it is explicitly committed or rolled back.

Key Words Used in Oracle

Key Words Used in Oracle 
The Key words that are used in Oracle are ::
a) Committing :: A transaction is said to be committed when the transaction makes permanent changes resulting from the SQL statements.
b) Rollback :: A transaction that retracts any of the changes resulting from SQL statements in Transaction.
c) SavePoint :: For long transactions that contain many SQL statements, intermediate markers or savepoints are declared. Savepoints can be used to divide a transaction into smaller points.
d) Rolling Forward :: Process of applying redo log during recovery is called rolling forward.
e) Cursor :: A cursor is a handle ( name or a pointer) for the memory associated with a specific stamen. A cursor is basically an area allocated by Oracle for executing the Sql Statement. Oracle uses an implicit cursor statement for Single row query and Uses Explicit cursor for a multi row query.
f) System Global Area(SGA) :: The SGA is a shared memory region allocated by the Oracle that contains Data and control information for one Oracle Instance. It consists of Database Buffer Cache and Redo log Buffer.
g) Program Global Area (PGA) :: The PGA is a memory buffer that contains data and control information for server process.
g) Database Buffer Cache :: Database Buffer of SGA stores the most recently used blocks of database data. The set of database buffers in an instance is called Database Buffer Cache.
h) Redo log Buffer :: Redo log Buffer of SGA stores all the redo log entries.
i) Redo Log Files :: Redo log files are set of files that protect altered database data in memory that has not been written to Data Files. They are basically used for backup when a database crashes.
j) Process :: A Process is a 'thread of control' or mechanism in Operating System that executes series of steps.

What are snap shots and views
Snapshots are mirror or replicas of tables. Views are built using the columns from one or more tables. The Single Table View can be updated but the view with multi table cannot be updated

What are the OOPS concepts in Oracle. 
Oracle does implement the OOPS concepts. The best example is the Property Classes. We can categorize the properties by setting the visual attributes and then attach the property classes for the objects. OOPS supports the concepts of objects and classes and we can consider the property classes as classes and the items as objects

What is the difference between candidate key, unique key and primary key 
Candidate keys are the columns in the table that could be the primary keys and the primary key is the key that has been selected to identify the rows. Unique key is also useful for identifying the distinct rows in the table.)

What is concurrency 
Concurrency is allowing simultaneous access of same data by different users. Locks useful for accesing the database are
a) Exclusive
The exclusive lock is useful for locking the row when an insert,update or delete is being done.This lock should not be applied when we do only select from the row.
b) Share lock
We can do the table as Share_Lock as many share_locks can be put on the same resource.

Previleges and Grants 
Previleges are the right to execute a particulare type of SQL statements. e.g :: Right to Connect, Right to create, Right to resource Grants are given to the objects so that the object might be accessed accordingly.The grant has to be given by the owner of the object

Table Space,Data Files,Parameter File, Control Files in oracle

Table Space,Data Files,Parameter File, Control Files 

Table Space :: The table space is useful for storing the data in the database.When a database is created two table spaces are created.
a) System Table space :: This data file stores all the tables related to the system and dba tables
b) User Table space :: This data file stores all the user related tables
We should have seperate table spaces for storing the tables and indexes so that the access is fast.
Data Files :: Every Oracle Data Base has one or more physical data files.They store the data for the database.Every datafile is associated with only one database.Once the Data file is created the size cannot change.To increase the size of the database to store more data we have to add data file.
Parameter Files :: Parameter file is needed to start an instance.A parameter file contains the list of instance configuration parameters e.g.::
db_block_buffers = 500
db_name = ORA7
db_domain = u.s.acme lang
Control Files :: Control files record the physical structure of the data files and redo log files
They contain the Db name, name and location of dbs, data files ,redo log files and time stamp.

Physical Storage of the Data 
The finest level of granularity of the data base are the data blocks.
Data Block :: One Data Block correspond to specific number of physical database space
Extent :: Extent is the number of specific number of contigious data blocks.
Segments :: Set of Extents allocated for Extents. There are three types of Segments
a) Data Segment :: Non Clustered Table has data segment data of every table is stored in cluster data segment
b) Index Segment :: Each Index has index segment that stores data
c) Roll Back Segment :: Temporarily store 'undo' information

What are the Pct Free and Pct Used 
Pct Free is used to denote the percentage of the free space that is to be left when creating a table. Similarly Pct Used is used to denote the percentage of the used space that is to be used when creating a table
eg.:: Pctfree 20, Pctused 40

What is Row Chaining 
The data of a row in a table may not be able to fit the same data block.Data for row is stored in a chain of data blocks .

What is a 2 Phase Commit 
Two Phase commit is used in distributed data base systems. This is useful to maintain the integrity of the database so that all the users see the same values. It contains DML statements or Remote Procedural calls that reference a remote object. There are basically 2 phases in a 2 phase commit.
a) Prepare Phase :: Global coordinator asks participants to prepare
b) Commit Phase :: Commit all participants to coordinator to Prepared, Read only or abort Reply

What is the difference between deleting and truncating of tables 
Deleting a table will not remove the rows from the table but entry is there in the database dictionary and it can be retrieved But truncating a table deletes it completely and it cannot be retrieved.

What are mutating tables 
When a table is in state of transition it is said to be mutating. eg :: If a row has been deleted then the table is said to be mutating and no operations can be done on the table except select.

What are Codd Rules 
Codd Rules describe the ideal nature of a RDBMS. No RDBMS satisfies all the 12 codd rules and Oracle Satisfies 11 of the 12 rules and is the only Rdbms to satisfy the maximum number of rules.

What is Normalisation ? - oracle

What is Normalisation ?

Normalisation is the process of organising the tables to remove the redundancy.There are mainly 5 Normalisation rules.
a) 1 Normal Form :: A table is said to be in 1st Normal Form when the attributes are atomic
b) 2 Normal Form :: A table is said to be in 2nd Normal Form when all the candidate keys are dependant on the primary key
c) 3rd Normal Form :: A table is said to be third Normal form when it is not dependant transitively

What is the Difference between a post query and a pre query 
A post query will fire for every row that is fetched but the pre query will fire only once.

Deleting the Duplicate rows in the table 
We can delete the duplicate rows in the table by using the Rowid

Can U disable database trigger? How? 
Yes. With respect to table
ALTER TABLE TABLE
[[ DISABLE all_trigger ]]

What is pseudo columns ? Name them? - oracle

What is pseudo columns ? Name them? 
A pseudocolumn behaves like a table column, but is not actually stored in the table. You can select from pseudocolumns, but you cannot insert, update, or delete their values. This section describes these pseudocolumns:
* CURRVAL
* NEXTVAL
* LEVEL
* ROWID
* ROWNUM

How many columns can table have? 
The number of columns in a table can range from 1 to 254.

Is space acquired in blocks or extents ? 
In extents .

What is clustered index? 
In an indexed cluster, rows are stored together based on their cluster key values . Can not applied for HASH.

What are the datatypes supported By oracle (INTERNAL)? 
Varchar2, Number,Char , MLSLABEL.

What are attributes of cursor? 
%FOUND , %NOTFOUND , %ISOPEN,%ROWCOUNT

Can you use select in FROM clause of SQL select ? 
Yes.

trigger are created when master -detail relay

Which trigger are created when master -detail relay?

master delete property
* NON-ISOLATED (default)
a) on check delete master
b) on clear details
c) on populate details
* ISOLATED
a) on clear details
b) on populate details
* CASCADE
a) per-delete
b) on clear details
c) on populate details

which system variables can be set by users? 
SYSTEM.MESSAGE_LEVEL
SYSTEM.DATE_THRESHOLD
SYSTEM.EFFECTIVE_DATE
SYSTEM.SUPPRESS_WORKING

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.