oracle pl/sql 小知识

1. procedure 或者 function 中 对 null 和 ” 的判断

CREATE OR REPLACE PROCEDURE TEST(PARA IN VARCHAR2)
IS
BEGIN
IF PARA = '' THEN
DBMS_OUTPUT.PUT_LINE('I AM '''' !');
ELSIF PARA IS NULL THEN
DBMS_OUTPUT.PUT_LINE('I AM NULL');
ELSE
DBMS_OUTPUT.PUT_LINE('NO TEST');
END IF;
END;

测试结果：

exec TEST('');
I AM NULL

PL/SQL procedure successfully completed.

SQL> exec TEST(' ');
NO TEST

PL/SQL procedure successfully completed.

结论：

PARA = ” 没有什么实际效果，如果是赋值还可，比较就算了

2. 变量赋值

请使用 := 而不是 =

CREATE OR REPLACE PROCEDURE TEST2(OPER_TYPE IN VARCHAR2)
IS
v_staff_str varchar2(50) ;
BEGIN
v_staff_str := ' and staff_id= 100000 '  ;
DBMS_OUTPUT.PUT_LINE(v_staff_str||' 1');
END;

CREATE OR REPLACE PROCEDURE TEST2(OPER_TYPE IN VARCHAR2)
IS
v_staff_str varchar2(50) := ' and staff_id= 100000 '  ;
BEGIN
-- v_staff_str  ;
DBMS_OUTPUT.PUT_LINE(v_staff_str||' 1');
END;

CREATE OR REPLACE PROCEDURE TEST2(OPER_TYPE IN VARCHAR2)
IS
BEGIN
-- v_staff_str  ;
declare v_staff_str varchar2(50)  ;
begin
v_staff_str := ' and staff_id = 100000 ' ;
DBMS_OUTPUT.PUT_LINE(v_staff_str||' 1');
end;
END;

CREATE OR REPLACE PROCEDURE TEST2(OPER_TYPE IN VARCHAR2)
IS
BEGIN
-- v_staff_str  ;
declare v_staff_str varchar2(50) := ' and staff_id = 100000 '  ;
begin
DBMS_OUTPUT.PUT_LINE(v_staff_str||' 1');
end;
END;

3.传入参数和表列名相同

传入参数将会被覆盖

CREATE OR REPLACE PROCEDURE TEST2(OPER_TYPE IN VARCHAR2)
IS
v_staff_str    varchar2(50);
BEGIN
DBMS_OUTPUT.PUT_LINE(OPER_TYPE||' 1');
insert into tmp_s
select OPER_TYPE from table1 log
inner join table2 staff  staff.staff_id=log.staff_id
where log.seqid=37968813;
END;

测试结果：

SQL> exec TEST2(‘haha2’);

haha2 1

PL/SQL procedure successfully completed.

SQL> select * from tmp_s;

STAFF_CODE
---------------
hehe
haha
3PD

结论：

haha2 没有插入，被表列覆盖