Oracle ×Ó³ÌÐò²ÎÊýģʽ,IN,OUT,NOCOPY

Oracle ×Ó³ÌÐò²ÎÊýģʽÖ÷ÒªÓÐIN,OUT,NOCOPY,INºÍOUT¿ÉÒÔ×éºÏ,OUTºÍNOCOPYÒ²¿ÉÒÔ×éºÏʹÓÃ.
INÖ÷ÒªÓÃÓÚ´«Èë²ÎÊý,¿ÉÒÔÊDZäÁ¿,³£Á¿,±í´ïʽ,ÔÚ×Ó³ÌÐòÄÚ²¿²»ÄܸıäÆäÖµ.
DECLARE
n NUMBER := 10;
PROCEDURE do_something (
n1 IN NUMBER) IS
BEGIN
dbms_output.put_line(n1); -- prints 10
--n1:=20; --illegal assignment.
END;
BEGIN
do_something(n);
do_something(20);
END;
OUTģʽÓÃÓÚ·µ»ØÖµ,±ØÐë´«Èë±äÁ¿µ÷ÓÃ,±äÁ¿µÄ³õʼµÄÖµ²»»á´«¸øÐÎʽ²ÎÊý,Èç<<1>>Ëùʾ.
ÐβεÄÖµÔÚ×Ó³ÌÐò·µ»Øʱ(²»ÊÇÔÚÐÎʽ²ÎÊý¸Ä±äʱ)²Åcopy¸øʵ²Î,
,Èç<<2>>Ëùʾ,Èç¹ûÔÚ
·µ»Ø֮ǰ·¢ÉúÒì³£,ʵ¼Ê²ÎÊýµÄÖµ²»»á±»¸Ä±ä.
DECLARE
n NUMBER := 10;
PROCEDURE do_something (
n1 OUT NUMBER) IS
BEGIN
dbms_output.put_line('before assign: ' || n1); -- prints none <<1>>
n1:=20;
dbms_output.put_line('before return: ' || n); -- prints 10 <<2>>
END;
BEGIN
do_something(n);
dbms_output.put_line('after return: ' || n); -- prints 20
END;
NOCOPYģʽÓÃÓÚÏÞ¶¨OUTģʽÔÚµ÷ÓÃʱÊDz»ÊÇÒÔ´«ÒýÓõķ½Ê½½øÐÐ(ËüÖ»ÊÇÒ»¸ö±àÒëÆ÷°µÊ¾,²»Ò»¶¨×ÜÊÇÆð×÷ÓÃ),ĬÈÏÇé¿öÏÂ,OUTģʽµÄ²ÎÊýÊÇÒÔ´«ÖµµÄ·½Ê½½øÐе÷ÓõÄ.
INÖ÷ÒªÓÃÓÚ´«Èë²ÎÊýµÄ,ËäÈ»n2 := 20±»µ÷ÓÃ,µ«ÊÇÒªµ½·µ»ØµÄʱºò²ÅÉúЧ.Èç<<1>>Ëùʾ.
NOCOPYÊÇ´«ÒýÓÃ,»áÔÚ¸³ÖµµÄʱºòÁ¢¼´ÉúЧ
,Èç<<2>>Ëùʾ,Èç¹ûÔÚ
·µ»Ø֮ǰ·¢ÉúÒì³£,ʵ¼Ê²ÎÊýµÄÖµÒ²»á±»¸Ä±ä.
ÓÉÓÚOUT²ÎÊýÔÚ
×Ó³ÌÐò·µ»ØµÄʱºò»á½«Öµcopyµ½Êµ¼Ê²ÎÊý,ËùÒÔµ÷ÓÃÍêºónµÄֵΪ20,Èç<<3>>Ëùʾ.
DECLARE
n NUMBER := 10;
PROCEDURE do_something (
n1 IN NUMBER,
n2 IN OUT NUMBER,
n3 IN OUT NOCOPY NUMBER) IS
BEGIN
n2 := 20;
dbms_output.put_line(n1); -- prints 10<<1>>
n3 := 30;
dbms_output.put_line(n1); -- prints 30 <<2>>
END;
BEGIN
do_something(n, n, n);
dbms_output.put_line(n); -- prints 20 <<3>>
END;