Define the terms primary key foreign key and also the
difference between primary and the unique key
Answer Posted / pugal
Primary Key : The primary key of a relational table
uniquely identifies each record in the table
Foreign Key : These keys are used to create relationships
between tables.
Unique Key : In relational database design, a unique key is
a candidate key to uniquely identify each row in a table. A
unique key comprises a single column or set of columns
Difference between primary and unique key :
primary key not allows null values
unique key allows null values
Is This Answer Correct ? | 33 Yes | 12 No |
Post New Answer View All Answers
Why do I get java.lang.abstractmethoderror when trying to load a blob in the db?
How to shutdown your 10g xe server from command line?
When do we use group by clause in a sql query?
Please explain compound trigger in oracle?
What is the difference between substr and instr?
What is a snapshot in oracle database?
What is the difference between alert log file and tarce file ?
How to establish administrator authentication to the server?
What is the difference between postgresql and oracle?
Explain the use of indexes option in exp command.
How to create a new view in oracle?
How to create a temporary table in oracle?
What is a dead lock in oracle?
Explain an exception?
How to manage transaction isolation level?