Cursor

From Oracle FAQ

A cursors is a pointer used to fetch rows from a result set. One can think of a cursor as a data structure that describes the results returned from a SQL SELECT statement. One of the variables in this structure is a pointer to the next record to be fetched from the query results.

Note that if you do repetitive stuff inside a loop and you fail to close your cursors, you would soon run into the ORA-01000: maximum number of open cursors exceeded error.

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PL/SQL example

PL/SQL example opening a curosr and fetching data from it in a loop:

DECLARE
  CURSOR c1 IS SELECT table_name FROM all_tables;
  v_table_name all_tables.table_name%TYPE;
  v_count      INTEGER := 1;
BEGIN
  OPEN c1;
  LOOP
     FETCH c1 INTO v_table_name;
     IF c1%notfound OR v_count > 2000 THEN
       EXIT;
     END IF;
     v_count := v_count + 1;
  END LOOP;

  -- Does cursor need to be closed
  IF c1%ISOPEN THEN  -- cursor is open
     CLOSE c1;
  END IF;

  dbms_output.put_line('Rows processed: '||v_count);
END;
/

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