Cursors

• Can declare a cursor on a relation or query statement (which generates a relation).

• Can open a cursor, and repeatedly fetch a tuple then move the cursor, until all tuples have been retrieved.

  • Can use a special clause, called ORDER BY, in queries that are accessed through a cursor, to control the order in which tuples are returned.
    • Fields in ORDER BY clause must also appear in SELECT clause.
  • The ORDER BY clause, which orders answer tuples, is only allowed in the context of a cursor.

• Can also modify/delete tuple pointed to by a cursor.

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