FIRST and LAST methods

obclient> DECLARE
  TYPE numlist IS TABLE OF NUMBER INDEX BY VARCHAR2(5);
  nl NUMLIST;

  PROCEDURE print_first_and_last IS
  BEGIN
    DBMS_OUTPUT.PUT_LINE('FIRST = ' || nl.FIRST);
    DBMS_OUTPUT.PUT_LINE('LAST = ' || nl.LAST);
  END print_first_and_last;

BEGIN
  nl('A') := 2;
  nl('C') := 4;
  nl('D') := 6;
  nl('E') := 8;
  nl('B') := 10;

  DBMS_OUTPUT.PUT_LINE('Before deleting:');
  print_first_and_last;

  nl.DELETE('A');
  nl.DELETE('E');

  DBMS_OUTPUT.PUT_LINE('After deleting:');
  print_first_and_last;
END;
/
Query OK, 0 rows affected

Before deleting:
FIRST = A
LAST = E
After deleting:
FIRST = B
LAST = D

obclient> DECLARE
  TYPE players IS VARRAY(5) OF VARCHAR2(20);   
  name PLAYERS;

  PROCEDURE print_name (heading VARCHAR2) IS
  BEGIN
    DBMS_OUTPUT.PUT_LINE(heading);

    IF name IS NULL THEN
      DBMS_OUTPUT.PUT_LINE('Does not exist');
    ELSIF name.FIRST IS NULL THEN
      DBMS_OUTPUT.PUT_LINE('No members');
    ELSE
      FOR i IN name.FIRST..name.LAST LOOP
        DBMS_OUTPUT.PUT_LINE(i || '. ' || name(i));
      END LOOP;
    END IF;

    DBMS_OUTPUT.PUT_LINE('---');
  END;

BEGIN
  print_name('Team Members:');

  name := PLAYERS();  -- No team members.
  print_name('Team Members:');

  name := players('Andrew', 'Barton');
  print_name('Team Members:');
  name := players('Charles', 'Carl', 'James', 'Gary','Brian');
  print_name('New Team Members:');
END;
/
Query OK, 0 rows affected

Team Members:
Does not exist
---
Team Members:
No members
---
Team Members:
1. Andrew
2. Barton
---
New Team Members:
1. Charles
2. Carl
3. James
4. Gary
5. Brian
---

obclient> DECLARE
  TYPE players IS TABLE OF VARCHAR2(20);   
  name PLAYERS;

  PROCEDURE print_name (heading VARCHAR2) IS
  BEGIN
    DBMS_OUTPUT.PUT_LINE(heading);

    IF name IS NULL THEN
      DBMS_OUTPUT.PUT_LINE('Does not exist');
    ELSIF name.FIRST IS NULL THEN
      DBMS_OUTPUT.PUT_LINE('No members');
    ELSE
      FOR i IN name.FIRST..name.LAST LOOP
        DBMS_OUTPUT.PUT_LINE(i || '.');
        IF name.EXISTS(i) THEN
          DBMS_OUTPUT.PUT_LINE(name(i));
        ELSE
          DBMS_OUTPUT.PUT_LINE('TBD');
        END IF;
      END LOOP;
    END IF;

    DBMS_OUTPUT.PUT_LINE('---');
  END;

BEGIN
  print_name('Team Members:');

  name := players();  -- A football team exists but has no players.
  print_name('Team Members:');

  name := players('Charles', 'Carl', 'James', 'Gary','Brian');  -- Add players to the team.
  print_name('Team Members:');

  name.DELETE(3,4);  -- Delete the third and fourth players.
  print_name('Current Team Members:');
END;
/
Query OK, 0 rows affected

Team Members:
Does not exist
---
Team Members:
No members
---
Team Members:
1.
Charles
2.
Carl
3.
James
4.
Gary
5.
Brian
---
Current Team Members:
1.
Charles
2.
Carl
3.
TBD
4.
TBD
5.
Brian
---