15일차 # 3-14: Scope and Visibility

  * Scope: Lifetime <= 변수는 선언된 블럭 내 존재하고 블럭을 빠져나가면 소멸

  * Visibility: Accessibility without help

<<amu>>      --> qualifier (한정어)

DECLARE

 father_name VARCHAR2(20) := 'Patrick';

 date_of_birth DATE := '20-Apr-1972';

BEGIN

DECLARE

 child_name VARCHAR2(20) :='Mike';

 date_of_birth DATE :='12-Dec-2002';

BEGIN

①

 DBMS_OUTPUT.PUT_LINE('Father''s Name: '||father_name);

 DBMS_OUTPUT.PUT_LINE('Date of Birth:  '||amu.date_of_birth);

 DBMS_OUTPUT.PUT_LINE('Child''s Name:  '||child_name);

 DBMS_OUTPUT.PUT_LINE('Date of Birth:  '||date_of_birth);

END;

②

DBMS_OUTPUT.PUT_LINE('Date of Birth: '||date_of_birth);

END;

/

- scope at ①: amu.father_name, amu.date_of_birth, chid_name, date_of_birth

  ②: amu.fatehr_name, amu_date_of_birth

- visibility at ①: amu.father_name, amu.date_of_birth, chid_name, date_of_birth

②: amu.father_name, amu.date_of_birth

  * scope를 벗어나면 변수는 메모리에서 제거됨