what is the different between unique+not null & primary key,

Answer Posted / giri

unique:it does not allow duplicate values but it allow null values.
not null:It does not allow null values but allow duplicate values.
primary:It does not allow both duplicate and null values.

Is This Answer Correct ?    0 Yes 0 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

What does the hierarchical profiler does?

784


Which version of sql do I have?

781


How to prepare for oracle pl sql certification?

815


Why do we use subquery?

736


Can we create table inside stored procedure?

716


Explain cursor types?

773


how would you write a query to select all teams that won either 2, 4, 6 or 8 games? : Sql dba

1115


Is primary key a clustered index?

718


What are the steps for performance tuning.

1060


Are dml statements autocommit?

798


What are the different types of database management systems?

749


What is a record in pl/sql?

788


What pl/sql package consists of?

853


How exception handling is done in advance pl/sql?

693


how many groups of data types? : Sql dba

762