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.
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Answer / 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.
| Is This Answer Correct ? | 6 Yes | 0 No |
Answer / shwetalguglanicse
Primary key can be assigned to only 1 column in the table but
this is not with unique key
And UK allow duplicate value but PK does not .
| Is This Answer Correct ? | 2 Yes | 8 No |
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