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

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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

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