游标的几种写法

SELECT empno,ename,job,sal  from emp

/*******
FOR  游标
*******/

DECLARE
    --定义游标
    CURSOR C_MAN IS
        SELECT * FROM EMP WHERE JOB = 'MANAGER';
    --定义游标的行(在FOR语句中，这个可以不用定义）
   -- C_ROW C_MAN%ROWTYPE;
BEGIN
    --循环游标查询 行.字段 (访问)
    FOR C_ROW IN C_MAN LOOP
        DBMS_OUTPUT.PUT_LINE(C_ROW.EMPNO);
        --exit when C_MAN % NOTFOUND = FALSE;
    END LOOP;
END;


/*******
FOR  游标  更新当前行
     where ... UPDATE  OF  字段
      update ...where ..FOR CURRENT 游标名
*******/
DECLARE  
        CURSOR c_table IS SELECT * FROM emp WHERE UPPER(Job)='MANAGER' FOR UPDATE OF sal;
BEGIN
        FOR c_row IN c_table LOOP
                  IF c_row.empno=7566 THEN
                          UPDATE emp SET sal=sal-0.1 WHERE CURRENT OF c_table;
                  END IF;
        END LOOP;       
        COMMIT; 
END;


/*******
FOR  游标  简洁
*******/
BEGIN
FOR c_table IN(SELECT * FROM emp) LOOP
       IF c_table.empno=7566 THEN
              dbms_output.put_line(c_table.sal);
       END IF;
END LOOP;
END;



/*******
FETCH 游标    读取行
*******/
DECLARE 
        CURSOR c_table IS
        SELECT * FROM emp WHERE UPPER(job)='MANAGER';
        c_row c_table%ROWTYPE;
BEGIN
        --打开游标
        OPEN c_table;
        --循环体
        LOOP
                --读取一行
                FETCH c_table INTO c_row;
                       dbms_output.put_line(c_row.empno||'-'||c_row.ename||'-'||c_row.job||'-'||c_row.sal);
                --退出条件
                EXIT WHEN c_table%NOTFOUND;
        END LOOP;
        --关闭游标
        CLOSE c_table;
END;


/*******
FETCH 游标    读取列
*******/
DECLARE 
        v_job emp.job%TYPE;
        v_sal emp.sal%TYPE;
        CURSOR c_table IS SELECT job,sal FROM emp WHERE empno IN(7369,7499) ;
BEGIN
        OPEN c_table;
        LOOP
             FETCH c_table INTO v_job,v_sal;
             EXIT WHEN c_table%NOTFOUND;
             dbms_output.put_line(v_job||to_char(v_sal));
        END LOOP;
        CLOSE c_table;
        --COMMIT;
END;