1.you can assign UK + NN TO A COLUMN behave like PRIMARY KEY(PK) but (UK +

WHAT IS THE DIFFERENCE BETWEEN PRIMARY KEY(PK) CONSTRAINT
AND UNIQUE KEY(UK) + NOT NULL(NN) CONSTRAINT ASSIGN TO A
COLUMN ?
INSTEAD OF ASSIGNING PK ,WE CAN ASSIGN UK + NN TO A COLUMN.
WHAT ARE THE MARRITS AND DEMARITS BETWEEN THE ABOVE TWO?THE
ABOVE TWO ARE SAME,THEY DON'T ALLOW DUPLICATE AS WELL AS
NULL VALUES.

Question Posted / adil khan

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Answer Posted / adil khan

1.you can assign UK + NN TO A COLUMN behave like PRIMARY KEY(PK)
but (UK + NN) can not make any relation with any other table.
where as PRIMARY KEY(PK) can make relation with others tables.

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