CREATE TABLE PARENT
(
  COL1  NUMBER                                  NOT NULL,
  COL2  NUMBER                                  NOT NULL);
--
CREATE TABLE CHILD
(
  COLA  NUMBER                                  NOT NULL,
  COL1  NUMBER,
  COL2  NUMBER);
--
ALTER TABLE PARENT ADD (
  CONSTRAINT PARENT_PK PRIMARY KEY (COL1, COL2));
--
ALTER TABLE CHILD ADD (
  CONSTRAINT CHILD_PK PRIMARY KEY (COLA));
--
ALTER TABLE CHILD ADD (
  CONSTRAINT CHILD_FK_TO_PARENT FOREIGN KEY (COL1, COL2) 
    REFERENCES PARENT (COL1,COL2));
--
insert into parent values (1, 1);
insert into child values (100, 1, 1);
--
alter session set sql_trace true;
delete parent;
alter session set sql_trace false;
-----------------------------------
--Extract from the trace file:
-----------------------------------
select count(1)
from
 "SCOTT"."CHILD" where "COL1" = :1 and "COL2" = :2

--
-- then the pl/sql takes over to evaluate the result of the select...
--