Vinod Tuteja

• Jun 14th, 2013

Main Difference : Referential
Index is created in both Cases (Unique and Primary key Constraint )

But can't references Columns with combination of UNIQUE and NOT NULL. Like in Primary key ,we Can references primary key to make foreign key constraint .

z_ashwini

 Profile Answers by z_ashwini Questions by z_ashwini

• Jan 13th, 2012

Eg: Consider table emp with EMP_ID,EM|NAME,ADD columns You can define the column e_name as Unique constraint. DECLARE e_name number(10) NOT NULL; BEGIN ... .. END: Primary key cannot have NU...

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There are 2 tables, A and B having 3 rows each. What will be result on executing the following query? : SQL> select * from A,B

Raju TT

• Jun 11th, 2013

Cross join -cartesian product :Table a no. of rows (3) * Table b no.of rows (3)= cross join query returns 9 rows

Code
 

Arpit Agrawal

• May 24th, 2013

Here simply answer would be 6. Since a is having 2 rows and b is having 3 rows. And we go for Cartesian join, which means 3*2=6.

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rajkumar1237

 Profile Answers by rajkumar1237 Questions by rajkumar1237

• Apr 27th, 2013

OCI means::oracle call interface.is a interface api used to access oracle database from C programs. Data Guard stands for it is multiple DB servers environment configured for Physical as well as Logic...

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In what ways can data be copied from one table to another?

Neeraj Saxena

• Apr 12th, 2013

You can copy the data from one table to another with the help of below Query:

Suppose dummy is the main table and we need to copy the data from dummy_120413 table.

Create tabel dummy_120413 as Select * from dummy;

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rayavarapu

 Profile Answers by rayavarapu Questions by rayavarapu

• Jan 23rd, 2013

Null is not a value and not a string. It is unknown it is maximum in descending order and minimum value in ascending order.

Sandeep

• Mar 7th, 2012

Char(0)

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Hasan

• Dec 15th, 2012

Truncate is a ddl...delete is dml
cannot rollback data in truncate...rollback data in delete
truncate -delete entire data not structure...it delete specific datas

VASU

• Oct 20th, 2012

By using delete we have to delete particular records only..
If we use truncate we cannot retrieve the data permanently...

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What is an autonomous transaction?

Sonal

• Nov 8th, 2012

The AUTONOMOUS_TRANSACTION pragma changes the way a subprogram works within a transaction. A subprogram marked with this pragma can do SQL operations and commit or roll back those operations, without ...

VASU

• Oct 20th, 2012

BY USING AUTONOMOUS TRANSACTION
WE GET THE FOLLOWING ADVANTAGES
WE PROCEDURE HAVING TRANSACTIONS STATEMENTS WE CALL PROCEDURE AUTOMATICALLY EFFECT THE ABOVE TRANSACTIONS ALSO TO OVERCOME THAT PROBLEM WE HAVE TO USE AUTONOMOUS TRANSACTION..

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What are the types of collection in PL/SQL? What is the advantage of nested tables?

pawan

• Nov 6th, 2012

Varrays,nested tables,index by tables are oracle collection.Index by tables also known as associative array similar to hashtables in java. Varrays are like arrays in java static in nature need to d...

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Hi, What is nocopy parameter in oracle procedure. what is the use of it. In which situation,we can use the nocopy parameter.Thanks,Saravanan.P

Himansu

• Nov 6th, 2012

In procedure,Function there are three types of parameter is there. eg-IN, OUT, INOUT. IN parameter is call by reference and OUT & INOUT are call by value. Always call by reference is faster than call ...

Saket

• Apr 3rd, 2012

Pass by reference: "IN" Case
Pass by value : "Out" or "IN OUT" Case which have the overhead of copying the value to new procedure parameter.
In order to make to Pass by reference we will use NOCOPY
Pass by reference: "OUT NOCOPY" or "IN OUT NOCOPY" which deals which the actual reference value.

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chiatanya

• Nov 5th, 2012

Implicit cursors are automatically generated,when a sql statement is processed where as

Explicit cursors are user defined.

VASU

• Oct 20th, 2012

Implicit cursors returns only single record..where as explicit cursor multiple records. But it process record by record.

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Can a type body be dropped without dropping the type specification?

ramya

• Oct 31st, 2012

When you drop a type body, the object type specification still exists, and you can re-create the type body. Prior to re-creating the body, you can still use the object type, although you cannot call the member functions.

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With what ways can we find out instance locks?

Jose George

• Oct 22nd, 2012

V$lock contains details of locks

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 Cursor  for loop implicitly declares %ROWTYPE as loop index,opens a cursor, fetches rows of values from active set into fields in the record and closeswhen all the records have been processed.      eg. FOR emp_rec IN C1 LOOP          salary_total := salary_total +emp_rec sal;         ...

vasu

• Oct 20th, 2012

Cursor for loop is the one by using this we need not to perform open, close, fetch operations of a cursor..

PRADEEP

• Oct 17th, 2012

If we use explicit cursor we need to open the cursor and fetching the data and close the cursor.

If we use cursor for loop cursor will open the cursor and fetching data and close the cursor automatically.

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How do you populate tables or data in Oracle 11g step by step?

Jose George

• Oct 17th, 2012

We can use SQL Loader too

Jose George

• Oct 16th, 2012

Depending on the situation one can use
external tables
or
UTL_FILE package

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 Database  trigger  is stored PL/SQL program unit associated with a specific database   table.   Usages   are  Audit  data  modifications,  Log  events transparently,   Enforce   complex  business  rules  Derive  column  values automatically,   Implement   complex   ...

KSPRADEEP

• Oct 17th, 2012

Trigger is data base object .Trigger is block of code it is executed automatically when dml operations are fired .

by using trigger we can do the auditing and perform a operation(modifications) on a tables (using dml operation)

krishnaindia2007

 Profile Answers by krishnaindia2007 Questions by krishnaindia2007

• May 6th, 2008

A database trigger is a named pl/sql block associated with a table and fires automatically when an event occurs or something happens. Data auditing , Implementing complex business rules, security are main uses of database triggers.

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 IN,OUT,IN-OUT parameters.

KSPRADEEP

• Oct 17th, 2012

Two modes of parameters are available to pass the parameter In and Out, the default parameter is IN. In : Lets you pass a value to subprogram being called.It can not be changed inside the parameter(...

g_sidhu

 Profile Answers by g_sidhu Questions by g_sidhu

• Jan 31st, 2008

IN (default): Passes a constant value from the calling environment into the procedureOUT     :Passes a value from the procedure to the calling environmentIN OUT  :Pa...

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KSPRDEEP

• Oct 17th, 2012

In parameter means it will insert the values
OUT parameters means it will print out put (pass values to output). If we not assigning any value to out parameter it will take (print) NULL value.

INOUT means it take values as input and out put

krishnaindia2007

 Profile Answers by krishnaindia2007 Questions by krishnaindia2007

• May 7th, 2008

1.There is no hard and fast rule about this. Whether to use INOUT or OUT depends upon the situation.2. If not assigned anything to OUT parameter it retuns NULL value.

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KSPRADEEP

• Oct 17th, 2012

Cluster are groups of one or more tables physically stores together to share common columns and are often used together

g_sidhu

 Profile Answers by g_sidhu Questions by g_sidhu

• Feb 6th, 2008

Clustering is a method of storing tables that are intimately related and often joined together into the same area on disk. For example, instead of the BOOKSHELF table being in one section of the disk ...

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We can create a column with' not null+unique' with out using primary key

PRADEEP

• Oct 17th, 2012

Primary key: set of columns is uniquely identified a rows of a table. It does not allow both nulls and duplicate values. If we use null values it will allow duplicate values but it does not allow n...

Radha

• Jul 14th, 2011

We can create NOTNULL and UNIQUE constraints on single column. Which indirectly means a Primary Key. But only a Primary Key column can be used as Foreign key column. Primary key provides a default...

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 %  TYPE  provides  the data type of a variable or a database column to that variable. % ROWTYPE  provides the record type that represents a entire row of a table or view or columns selected in the cursor. The advantages are : I. Need not  know about variable's data typeii.  If  the  database  definition of a column in a table changes, the...

PRADEEP

• Oct 16th, 2012

%rowtype is associated entire table(if we want to declare all columns then we need to declare %rowtype).

%type is associated with one column .(if we want to declare entire column then we need to declare %type).

Yaseen

• Aug 9th, 2012

If using %type and %rowtype , no need to know the the data type of the table column . and once the development is finished , the type of column is changed it will not effect the coding.

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