demonstrates the behavior of the DETERMINISTIC keyword.

    
SQL>
SQL> set echo on
SQL>
SQL> CREATE TABLE lecturer (
  2    id               NUMBER(5) PRIMARY KEY,
  3    first_name       VARCHAR2(20),
  4    last_name        VARCHAR2(20),
  5    major            VARCHAR2(30),
  6    current_credits  NUMBER(3)
  7    );

Table created.

SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
  2                VALUES (10001, 'Scott', 'Lawson','Computer Science', 11);

1 row created.

SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major, current_credits)
  2                VALUES (10002, 'Mar', 'Wells','History', 4);

1 row created.

SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
  2                VALUES (10003, 'Jone', 'Bliss','Computer Science', 8);

1 row created.

SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
  2                VALUES (10004, 'Man', 'Kyte','Economics', 8);

1 row created.

SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
  2                VALUES (10005, 'Pat', 'Poll','History', 4);

1 row created.

SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
  2                VALUES (10006, 'Tim', 'Viper','History', 4);

1 row created.

SQL>
SQL>
SQL> ALTER SESSION SET SQL_TRACE = TRUE;

Session altered.

SQL>
SQL> CREATE OR REPLACE FUNCTION lecturerStatus(
  2    p_NumCredits IN NUMBER)
  3    RETURN VARCHAR2 AS
  4  BEGIN
  5    IF p_NumCredits = 0 THEN
  6      RETURN 'Inactive';
  7    ELSIF p_NumCredits <= 12 THEN
  8      RETURN 'Part Time';
  9    ELSE
 10      RETURN 'Full Time';
 11    END IF;
 12  END lecturerStatus;
 13  /

Function created.

SQL>
SQL> SELECT id
  2    FROM lecturer
  3    WHERE SUBSTR(lecturerStatus(current_credits), 1, 20) =
  4      'Part Time';

        ID
----------
     10001
     10002
     10003
     10004
     10005
     10006

6 rows selected.

SQL>
SQL> CREATE OR REPLACE FUNCTION lecturerStatus(p_NumCredits IN NUMBER)
  2    RETURN VARCHAR2
  3    DETERMINISTIC AS
  4  BEGIN
  5    IF p_NumCredits = 0 THEN
  6      RETURN 'Inactive';
  7    ELSIF p_NumCredits <= 12 THEN
  8      RETURN 'Part Time';
  9    ELSE
 10      RETURN 'Full Time';
 11    END IF;
 12  END lecturerStatus;
 13  /

Function created.

SQL>
SQL> CREATE INDEX lecturer_index ON lecturer
  2    (SUBSTR(lecturerStatus(current_credits), 1, 20))
  3    COMPUTE STATISTICS;

Index created.

SQL>
SQL> ALTER SESSION SET QUERY_REWRITE_ENABLED = TRUE;

Session altered.

SQL> ALTER SESSION SET QUERY_REWRITE_INTEGRITY = TRUSTED;

Session altered.

SQL>
SQL> SELECT /*+ index(lecturer,lecturer_index) */ id
  2    FROM lecturer
  3    WHERE SUBSTR(lecturerStatus(current_credits), 1, 20) =
  4      'Part Time';

        ID
----------
     10001
     10002
     10003
     10004
     10005
     10006

6 rows selected.

SQL>
SQL> DROP INDEX lecturer_index;

Index dropped.

SQL>
SQL> drop table lecturer;

Table dropped.

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demonstrates the behavior of the DETERMINISTIC keyword. : Function Definition « Stored Procedure Function « Oracle PL / SQL

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