Oracle游标总结

Posted 2020-08-03 代码改变生活

1.声明游标

declare
teacher_id number(5);
teacher_name varchar2(5);
teacher_title varchar2(50);
teacher_sex char(1);

cursor teacher_cur is
    select tid,tiname,title,sex from teachers where tid<117;

2.打开游标

open 游标名;

declare
teacher_id number(5);
teacher_name varchar2(5);
teacher_title varchar2(50);
teacher_sex char(1);

cursor teacher_cur is
    select tid,tiname,title,sex from teachers where tid<117;
open teacher_cur;

3.提取游标

fetch 游标名 into 变量列表

declare
teacher_id number(5);
teacher_name varchar2(5);
teacher_title varchar2(50);
teacher_sex char(1);

cursor teacher_cur is
    select tid,tiname,title,sex from teachers where tid<117;
open teacher_cur;
fetch teacher_cur into tid,tinme,title,sex;

4.关闭游标

close 游标名

declare
    teacher_id number(5);
    teacher_name varchar2(5);
    teacher_title varchar2(50);
    teacher_sex char(1);

cursor teacher_cur is
    select tid,tiname,title,sex from teachers where tid<117;
open teacher_cur;
    fetch teacher_cur into tid,tinme,title,sex;
    Loop 
        EXIT WHEN NOT teacher_cur%FUND;
        IF teaher_sex = ‘M‘ THEN
            INSERT INTO MALE_TEACHERS(TID,TNAME,TITLE) VALUES();    
        ELSE 
            INSERT INTO FEMALE_TEACHERS(TID,TNAME,TITLE) VALUES(teacher_id,teacher_name,teacher_title);
        END IF;
    FETCH teacher_cur INTO teacher_id,teacher_name,teacher_title,teacher_sex;
    END LOOP;
CLOSE teacher_cur;
END;

使用显示游标:

1):使用前用游标名%ISOPEN检查打开状态,只有值为TRUE是才可使用

2):使用游标每次都要用%NOTFUND,%FUND确认是否返回成功

3):提取游标时对应变量个数一致

4):必须关闭游标释放资源

---

 

1.%fund是否找到有效行,是则为true 否则是false

open teacher_cur;
fetch teacher_cur into teacher_id,teacher_name,teacher_title,teacher sex;
loop 
exit when not teacher_cur%found;
end loop

　　SQL%fund

delete from teachers
    where tid=teacher_id;
if SQL%found then
    insert into success values(tid);
else
    insert into fail values(tid);
end if;

2.%NOTFOUND

OPEN teacher_cur;
FETCH teacher_cur INTO teacher_id,teacher_name,teacher_title,teacher_sex;
LOOP
    EXIT WHEN teacher_cur%NOTFOUND;
END LOOP

　　SQL%NOTFOUND

DELETE FROM TEACHERS
    WHERE TID = teacher_id;
IF SQL%NOTFOUND THEN
    INSERT INTO FALL VALUES(TID);
ELSE
    INSERT INTO SUCCESS VALUES(TID);
END IF;

3.%ROWCOUNT

该属性记录了游标抽取过的记录行数,也可以理解为当前游标所在的行号,这个属性在循环判断中有效

LOOP
    FETCH teacher_our INTO teacher_id,teacher_name,teacher_title,teacher_sex;
    EXIT WHEN teacher_cur%ROWCOUNT=10;--只抽取10条记录
    ...
    END LOOP;

用FOR语句控制游标的循环,系统隐含的定义了一个数据类型为%ROWCOUNT的记录,作为循环计数器,并将隐士的打开和关闭游标

FOR teacher_record in teacher_cur LOOP --teacher_record作为记录名,隐含的代开游标teacher_cur
    INSERT INTO TEMP TEACHERS(TID,TNAME,TITLE,SEX) VALUES(teacher_record,tid,teacher_record,tname,teacher_record,title,teacher_record.sex);
END LOOP

4.%ISOPEN

... ...

5.参数话游标:

DECLARE
--定义游标是带上参数CURSOR_ID
    CURSOR teacher_cur(CURSOR_id NUMBER) IS
        SELECT TNAME,TITLE,SEX FROM TEACHERS WHERE TID=CURSOR_id;--使用参数
BEGIN
    OPEN teacher_cur(my_tid);--带上参数
    LOOP
        FETCH teacher_cur INTO teacher_name,teacher_title,teacher_sex;
        EXIT WHEN teacher_cur%NOTFOUND;
        ...
    END LOOP;
    CLOSE teacher_cur;
END;