Answer / dj

Primary key creates Clustered Index.
Unique key creates non-clustered Index

Answer / sreesakthi

primary key will not allow null values whereas unique key
will allow null values.we have only one primary key per
table,but we can have more than one unique key per table

Answer / pralhad

Each table having only one PRIMARY KEY.And my contain many
UNIQUE KEYS.
PRIMARY KEY is identity of each row. UNIQUE KEY also
identity of each row.
BOTH keys will not contain repeated value.
BUT UNIQUE KEY will contain NULL value but PRIMAY key will
not contain NULL value.

Answer / satendra dixit

Primary Key
1. Not Null
2. One primary key can be defined at on table

Unique Key
1. May be Null
2. one or more then 1, can be implemented

Answer / saurabh

the no of primary key in a table is one but the no of
unique is more then one

Answer / mohan singh

Primary key contain non repetitive value and not null
value,and primary key is created on clustered index.In the
table their should be one primary key column.


Unique key contain non repetitive value but can contain
only one null value in the column.And unique key is created
on non clustered index.

Answer / pankaj kumar tiwari

primary key create index it means its value inserted in
sequence but in unique, we insert data in any order

Answer / niraj pratap singh

primary key has no null values whereas unique accepts null
values and in a table only one primary key is declared
whereas unique key is multiple in a table.

Answer / rinu

1)unique key can be null but primariy key cant be null.
2)primariy key can be refrenced to other table as FK.
3)we can have multiple unique key in a table but PK is one
and only one.
4)PK in itself is unique key.
5)a table can have more then one unique key column but a
table can have only one primary key column.
6)primary key creates clustered index but unique key
creates non clustered index.

Answer / ela tiku

1. Primary key does not allow Nill value whereas Unique key
allows Null values.

2. There can more than one Unique key for a table however
there is only one primary key for ant tanle.

2. Whenever a primary key is assigned by default a
Clustered Index is created whereas When a Unique key is
created a Non Index clustered index is created...

what's query optimization and without use of IN AND Exist can we get another way data from query

0 Answers  

How to shutdown your 10g xe server from command line?

0 Answers  

How do I limit the number of rows returned by an oracle query after ordering?

0 Answers  

What is the difference between normal and corelated subqueries?

2 Answers  

9)When information has to be stored w.r.t employees and their respective departments, which of the following is the Correct formulation of entries? A)Employee and department would together be represented as an entity. B)This is too less information to decide on entities. C)An employee would be one entity and a department would be another. D)Such a scenario cannot be modelled in RDBMS

2 Answers   Mind Tree,

What is the difference between hot backup and cold backup in oracle? Tell about their benefits also.

0 Answers  

How to delete a column in an existing table in oracle?

0 Answers  

Define the terms primary key foreign key and also the difference between primary and the unique key

2 Answers  

Explain what are the characteristics of data files?

0 Answers  

How would you go about verifying the network name that the local_listener is currently using?

0 Answers  

What is the implicit cursor in oracle?

0 Answers  

Explain the use of file option in exp command.

0 Answers