如何调试此SQL查询？

我运行了这段代码，但它不起作用（我希望得到一个结果集，但没有得到）：

但是如果我运行查询

select max(salary) from employees where hire_date between '2002-01-01' and '2003-12-31';

及

它们运行良好<代码>最高（工资）来自第二个查询的值为24000.00

这是我尝试练习的网站（问题34）

使用子查询进行筛选时，请使用“IN”子句而不是“=”

SELECT e.employee_id,
       e.first_name,
       e.last_name,
       e.salary,
       d.department_name,
       l.city
FROM   employees e
       JOIN departments d
         ON e.department_id = d.department_id
       JOIN locations l
         ON l.location_id = d.location_id
WHERE  e.salary IN (SELECT Max(salary)
                    FROM   employees
                    WHERE  hire_date BETWEEN '2002-01-01' AND '2003-12-31'); 

---

子查询缺少括号

SELECT e.employee_id,
       e.first_name,
       e.last_name,
       e.salary,
       d.department_name,
       l.city
FROM   employees e
       JOIN departments d
         ON e.department_id = d.department_id
       JOIN locations l
         ON l.location_id = d.location_id
WHERE  e.salary = (SELECT Max(salary)
                   FROM   employees
                   WHERE  hire_date BETWEEN '2002-01-01' AND '2003-12-31'); 

---

你说不工作是什么意思？我没有从查询中得到结果。我正在使用浏览器编写代码。这是一个侧面的网站注：根据SQL标准，此：

'2002-01-01'

是字符串文字，而此：

date'2002-01-01'

是日期文字。因此，在日期字符串前面加上单词

date

，以避免字符串/日期转换和可能出现的复杂情况（尽管不太可能有任何复杂情况）。

Max

without

groupby

将返回一条记录。所以

=

应该可以工作。

SELECT e.employee_id,
       e.first_name,
       e.last_name,
       e.salary,
       d.department_name,
       l.city
FROM   employees e
       JOIN departments d
         ON e.department_id = d.department_id
       JOIN locations l
         ON l.location_id = d.location_id
WHERE  e.salary IN (SELECT Max(salary)
                    FROM   employees
                    WHERE  hire_date BETWEEN '2002-01-01' AND '2003-12-31'); 

SELECT e.employee_id,
       e.first_name,
       e.last_name,
       e.salary,
       d.department_name,
       l.city
FROM   employees e
       JOIN departments d
         ON e.department_id = d.department_id
       JOIN locations l
         ON l.location_id = d.location_id
WHERE  e.salary = (SELECT Max(salary)
                   FROM   employees
                   WHERE  hire_date BETWEEN '2002-01-01' AND '2003-12-31');