Question

我是pl / sql的新手。我想要进行程序检查表员工是否存在empno emno大于100。如果存在至少一个，我想要退出循环。

如何修改以下代码？是不是我不知道;使用％NOTFOUND，％ROWCOUNT？

CREATE OR REPLACE procedure check_value
IS

cursor c1 is 
    select *
    from employess;

c1_values c1%ROWTYPE;

BEGIN

   open c1;
   fetch c1 into c1_values;
   loop
        if c1_values.EMPNO > 100 then
            DBMS_OUTPUT.put_line ('Found row with empno > 100');
        end if;
   end loop;
   close c1;

END;

提前感谢您的帮助。

Answer 1

如果你只是需要检查你是否拥有超过100的记录，你可以使用EXISTS声明，例如

DECLARE
    CURSOR c1 IS
    SELECT
        CASE
            WHEN EXISTS (
                SELECT
                    1
                FROM
                    employees
                WHERE
                    empno > 100
            ) THEN 1
            ELSE 0
        END AS empno_exists
    FROM
        dual;

    ln_empno_exists     PLS_INTEGER;

BEGIN
    OPEN c1;
    FETCH c1 INTO ln_empno_exists;
    CLOSE c1;

    DBMS_OUTPUT.PUT_LINE('Empno over 100 exists: '||CASE WHEN ln_empno_exists = 1 THEN 'TRUE' ELSE 'FALSE' END);

END;
/

编辑：如果您想在某些条件下获取行，则只需在WHERE语句中调整SELECT子句即可。这里有一个示例，通过一些方法来迭代所提取的记录：

DECLARE
    CURSOR c1 IS
    SELECT
        emp.*
    FROM
        employees emp
    WHERE
        empno > 100
    ;

    lr_c1_rec       c1%ROWTYPE;
BEGIN
    -- Using FOR loop
    DBMS_OUTPUT.PUT_LINE('START: Printing employees records where empno > 100');
    FOR rec IN c1
    LOOP
        DBMS_OUTPUT.PUT_LINE('empno = '||rec.empno);
    END LOOP;
    DBMS_OUTPUT.PUT_LINE('END: Printing employees records where empno > 100');



    -- Using a LOOP with EXIT clause
    DBMS_OUTPUT.PUT_LINE('START: Printing employees records where empno > 100');
    OPEN c1;
    LOOP
        FETCH c1 INTO lr_c1_rec;
        -- exit the loop when your cursor doesn't have any more records to be returned
        EXIT WHEN c1%NOTFOUND;

        DBMS_OUTPUT.PUT_LINE('empno = '||lr_c1_rec.empno);
    END LOOP;
    DBMS_OUTPUT.PUT_LINE('END: Printing employees records where empno > 100');

    -- Using WHILE loop
    DBMS_OUTPUT.PUT_LINE('START: Printing employees records where empno > 100');
    OPEN c1;
    FETCH c1 INTO lr_c1_rec;
    -- As long as cursor returns any values, iterate through the records returned
    WHILE c1%FOUND
    LOOP
        DBMS_OUTPUT.PUT_LINE('empno = '||lr_c1_rec.empno);
    END LOOP;
    DBMS_OUTPUT.PUT_LINE('END: Printing employees records where empno > 100');
END;
/

Answer 2

只需在找到您的价值后添加EXIT声明：

CREATE OR REPLACE procedure check_value IS
  cursor c1 is 
    select *
    from employess;

  c1_values c1%ROWTYPE;
BEGIN
   open c1;

   loop
     fetch c1 into c1_values;
     IF c1%NOTFOUND THEN EXIT;

     if c1_values.EMPNO > 100 then
       DBMS_OUTPUT.put_line ('Found row with empno > 100');
       EXIT;
     end if;
   end loop;

   -- The EXIT statement will drop you out of the loop and leave you here

   close c1;
END;

请注意，我在循环中移动了fetch并添加了％NOTFOUND检查。如果没有％NOTFOUND，代码永远不会知道光标没有数据，可能会进入无限循环。

Answer 3

为什么要定义游标，然后打开并获取它只需要完成   SQL但如果需要，那么使用FOR循环和EXIT条件   如上所述

下方。希望它有所帮助

CREATE OR REPLACE PROCEDURE check_value
IS
BEGIN
  FOR I IN
  (SELECT * FROM employess
  )
  LOOP
    IF I.EMPNO > 5 THEN
      DBMS_OUTPUT.put_line ('Found row with empno > 100');
      EXIT;
    END IF;
  END LOOP;
END;

PL / SQL Cursor只检查value是否大于某个值

3 个答案: