We can create more unique key in a table but we can not create more then o

IN A TABLE HAVE ONE COLUMN PRIMARY KEY..IT WILL NOT ALLOWS
NULL VALUES AND DUPLICATE VALUES..INSTEAD OF PRIMARY KEY
WHY CANT WE USE UNIQUE AND NOT NULL.THESE TWO ALSO DOESNT
ACCEPT NULL VALUES IN NOT NULL AND UNIQUE DOESNT ACCEPT
DUPLICATE VALUES?
SO WHAT IS THE DIFEERENCE BETWEEN(UNIQUE,NOT NULL) AND
PRIMARY KEY??????

Question Posted / prativa mishra

8 Answers
10516 Views
rsystems, I also Faced
E-Mail Answers

Answer Posted / prativa mishra

We can create more unique key in a table but we can not create more then one primary key in a table.At the time of primary key creation thr is a clusterd index created automatically and it sorts data physically. It helps in searching process which not possible in unique+notnull column

Is This Answer Correct ?

2 Yes

2 No

Post New Answer View All Answers

Please Help Members By Posting Answers For Below Questions

What are predefined functions in sql?

1045

What is trigger types of trigger?

1070

What are the parts of a sql statement?

1090

How to download oracle sql developer?

1110

Which sql statement is used to return only different values?

1004

When can we use the where clause and the having clause?

1020

How many primary keys can a table have?

1009

What is an exception in PL/SQL? What are the two types of exceptions?

1312

How is indexing done in search engines?

982

Can you join a table to itself?

1132

What is sql architecture?

1050

what is myisam? : Sql dba

1085

What is primary and foreign key?

1064

what is a database transaction? : Sql dba

1186

What are the different set operators available in sql?

1026