PL/SQL FOR 循环隐式游标

有2张桌子EMPLOYEES and DEPARTMENTS with department_id作为主键DEPARTMENTS和外键EMPLOYEES.

我想打印属于特定部门的所有员工姓名。我知道它可以通过 JOINS 或 JOINS 轻松实现EXPLICIT光标。 我想为什么不尝试使用 FOR 循环和IMPLICIT光标。

我的问题是这样写在语法上是否正确INTO像这样。如果是这样为什么不分配任何值？

DECLARE
    emp_dept_id employees.department_id%TYPE;
    emp_emp_id employees.employee_id%TYPE;
    emp_last_name employees.last_name%TYPE;
    dept_dept_id departments.department_id%TYPE;
    dept_dept_name departments.department_name%TYPE;
    v_count number DEFAULT 0;
BEGIN
    FOR i IN (SELECT DISTINCT department_id, department_name
                INTO dept_dept_id, dept_dept_name
        FROM departments)
    LOOP
        --v_COUNT := v_COUNT + 1;
        DBMS_OUTPUT.PUT_LINE('HELLO'||dept_dept_id||' '||dept_dept_name);
        FOR j IN (SELECT employee_id, last_name
            INTO emp_emp_id, emp_last_name
            FROM employees)
            --WHERE department_id=dept_dept_id)
        LOOP
            DBMS_OUTPUT.PUT_LINE(emp_emp_id||' '||emp_last_name);
            v_COUNT := v_COUNT + 1;
        END LOOP;
    END LOOP;
    DBMS_OUTPUT.PUT_LINE(v_COUNT);
END;

您不将 INTO 与隐式游标一起使用：

    DECLARE
        emp_dept_id employees.department_id%TYPE;
        emp_emp_id employees.employee_id%TYPE;
        emp_last_name employees.last_name%TYPE;
        v_count number DEFAULT 0;
    BEGIN
        FOR i IN (SELECT DISTINCT department_id, department_name
            FROM departments)
        LOOP
            --v_COUNT := v_COUNT + 1;
            DBMS_OUTPUT.PUT_LINE('HELLO'||i.department_id||' '||i.department_name);
            FOR j IN (SELECT employee_id, last_name
                INTO emp_emp_id, emp_last_name
                FROM employees)
                --WHERE department_id=i.department_id)
            LOOP
                DBMS_OUTPUT.PUT_LINE(emp_emp_id||' '||emp_last_name);
                v_COUNT := v_COUNT + 1;
            END LOOP;
        END LOOP;
        DBMS_OUTPUT.PUT_LINE(v_COUNT);
    END;
    /