Interested to Buy Any Domain ? << Click Here >> for more details...
Is primary key = unique key,not null?
If yes,please explain
IF No,please explain
- 8 Answers
- 18069 Views
- Genpact, I also Faced
- E-Mail Answers
Answer Posted / chandrika
if we define unique key column to not null
then first attempt it not allow to insert null value in
column but after inserting once we can edit its value to
null even if it is not null ( means its allow null)
if we assign primary key then its not allow (in every
situation it not allow null and duplication)
that is main difference between unique key and primery key
| Is This Answer Correct ? | 0 Yes | 7 No |
Post New Answer View All Answers
What is the difference between a hot backup and a cold backup in oracle?
Can objects of the same schema reside in different tablespace?
What are the execution control statements?
what is Single Byte Overhead...?
What are the oracle built-in data types?
How is it different from a normal table?
How to establish administrator authentication to the server?
How remove data files before opening a database?
How many types of database triggers exist?
What is a schema in oracle?
How to add a new column to an existing table in oracle?
What is an Oracle index?
What happens internally when the user types userID/password@string in SQL PLUS Thanks-Bhaskar
How to declare a local variable?
Explain the use of log option in exp command.
