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At the time of creation of table X, the database administrator specified Y as the Primary key. Later on he realized that instead of Y the combination of column P and Q should have been the primary key of the table. Based on this scenario, answer the following questions :(a) Is it possible to keep Y as well as the combination of P and Q as the primary key?(b) What statement(s) should be entered to change the primary key as per the requirement. |
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Answer» (i) No - A table can have only one primary key. (ii) ALTER TABLE X DROP PRIMARY KEY ALTER TABLE X ADD PRIMARY KEY(PQ) |
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