oracle夜未眠之二视图、函数、存储过程、触发器四连发

1、创建视图

CREATE  OR replace VIEW my_view(id,stuname,stupassword)) AS SELECT s.id,s.stuame,item.stupassword FROM stu s,stu_item item WHERE item.fid=stu.id;

2、使用视图

SELECT *  FROM  my_view WHERE stuname='testname';

3、查看视图创建语句

SELECT TEST FROM my_view

4、游标的创建和使用

DECLARE 
CURSOR my_cur IS SELECT *  FROM stu 
stus stu%ROWTYPE;
cunt NUMBER;

BEGIN
  IF my_cur%ISOPEN THEN 
    NULL;
  ELSE
    OPEN my_cur;
  END IF;
  
  FOR stus IN my_cur LOOP
    cunt := mu_cur%ROWCOUNT;
    dbms_output.put_line(stus.stuname);
  END LOOP
  
  END;

5、函数的创建和使用

CREATE OR REPLACE FUNCTION my_fun(sname stu.stuname%Type) RETURN NUMBER  AS 

re NUMBER;
BEGIN 
  SELECT COUNT(*) INTO re FROM stu WHERE stu.stuname = 'testname';
  RETURN re;
 END;
 
 SELECT my_fun('testname') FROM dual

6、存储过程的创建和使用

CREATE OR REPLACE PROCEDURE my_pro(sname stu.stuname) AS 

cunt NUMBER;

BEGIN
  SELECT COUNT(*) INTO cunt FROM stu s WHERE s.stuname=sname; 
  IF cunt = 0 THEN
    INSERT INTO stu(stuname) VALUES (sname);
  ELSE
    NULL;
  END IF;
END;

oracle中调用存储过程，如果是不带参数的可以将上面的格式as 改成is ,调用也可以直接使用call my_pro();

DECLARE 
 sname stu.stuname%TYPE;
BEGIN
 sname :='testname';
 my_pro(sname);
END;

7、触发器的创建和使用

CREATE  OR REPLACE TRIGGER my_tri_stu
BEFORE INSERT OR UPDATE OR DELETE ON stu FOR EACH ROW
DECLARE cunt NUMBER;
BEGIN
  SELECT COUNT(*) INTO cunt FROM stu WHERE stu.stuname='testname';
  IF cunt= 0  THEN 
    INSERT INTO stu(stuname) VALUES ('test');
  ELSIF
     DELETE FROM stu WHERE stuname='testname' ;
  END IF;
  
  CASE
    WHEN INSERT THEN 
      dbms_output.put_line('插入');
    WHEN UPDATE THEN 
      dbms_output.put_line('更新');
    WHEN DELETE THEN 
      dbms_output.put_line('删除');
  END CASE
END;