为什么我得不到我已提取的确切行数？

Question

我学习 PLSQL 已经 3 个月了。现在我正在练习显式游标。我写了一个简单的游标，我使用了属性 %ROWCOUNT 来查询 5 行员工，但我在屏幕上只收到了 4 名员工。为什么？

SET SERVEROUTPUT ON
DECLARE
  CURSOR cur_emp IS
    SELECT e.employee_id, e.last_name, d.department_id, d.department_name
    FROM employees e
    JOIN departments d
    ON (e.department_id = d.department_id);

  v_emp_id employees.employee_id%TYPE;
  v_emp_name employees.last_name%TYPE;
  v_dept_id departments.department_id%TYPE;
  v_dept_name departments.department_name%TYPE;
BEGIN
  OPEN cur_emp;
    LOOP
      FETCH cur_emp
      INTO v_emp_id, v_emp_name, v_dept_id, v_dept_name;
      EXIT WHEN cur_emp%ROWCOUNT = 5;
      DBMS_OUTPUT.PUT_LINE('EMPLOYEE ID: ' || v_emp_id || ' EMPLOYEE: ' ||
        v_emp_name || ' DEPARTMENT ID: ' || v_dept_id || ' DEPARTMENT NAME: ' ||
        v_dept_name);
    END LOOP;   
  CLOSE cur_emp;
END;
/

Answer 1

循环首先检查条件，所以要写 4 名员工，检查下一个员工的行数并退出循环，您必须将 ROWCOUNT > 5，ROWCOUNT = 6 或将 EXIT WHEN 条件移动到在您致电 DBMS_OUTPUT.

之后

为什么我得不到我已提取的确切行数？

Why Do I not get the exact numbers of rows that I've fetched?

sql

plsql

cursors