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More Object Database Concepts

More Object Database Concepts. Basic Functions and datatypes. Value, DREF and REF VARRAY. Value (returns value of a row). SQL> select value(p) from person p; VALUE(P)(PID, FIRSTNAME, LASTNAME, DOB) ------------------------------------------------------------------

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More Object Database Concepts

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  1. More Object Database Concepts

  2. Basic Functions and datatypes • Value, DREF and REF • VARRAY

  3. Value (returns value of a row) • SQL> select value(p) from person p; VALUE(P)(PID, FIRSTNAME, LASTNAME, DOB) ------------------------------------------------------------------ PERSON_T('121111111', 'Joe', 'Smith', '21-OCT-61') PERSON_T('121222222', 'John', 'Kelsey', '15-DEC-66')

  4. REF (returns the address of the row) SQL> select ref(p) from person p where lastname='Grand'; • REF(P) ----------------------------------------------------- 000040030A003C0F3289B74EAC4CA1BB4D0DD5C4F1F78900000017260

  5. DEREF (given a reference to a row, gets the row); • SELECT DEREF(s_obj.super) INTO p_obj FROM DUAL;

  6. Dual: dummy table • SQL> select sysdate from dual • SYSDATE • --------- • 22-SEP-03

  7. VARRAY: Variable length array • CREATE OR REPLACE TYPE student_array AS VARRAY(50) OF REF student_t;

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