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A foreign key is:

  • A.a column containing the primary key of another table.
  • B.used to define data types.
  • C.used to define null status.
  • D.all of the above are above correct.

Answer: A

Correct answer: a column containing the primary key of another table.

A foreign key is a column, or set of columns, holding values that appear as the primary key of some table - often another, though a recursive relationship makes it the same one. It is the sole mechanism by which relationships are represented, since the relational model has no pointers and every link is expressed by matching values.

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