Machine-translated by Google. Questions are authored in English.
Top

Discussion

A key:

  • A.must always be composed of two or more columns.
  • B.can only be one column.
  • C.identifies a row.
  • D.identifies a column.

Answer: C

Correct answer: identifies a row.

A key identifies rows, not columns, and it may consist of one attribute or several - a key of two or more is a composite key, but there is no requirement either way. What matters is that the combination be unique across the relation and minimal, so that no attribute could be dropped and uniqueness still hold.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.