SQL select查询使用连接，分组和聚合函数

I have two tables with the following fields

我有两个表格，包括以下字段

emp_table: emp_id, emp_name
salary_increase: emp_id, inc_date, inc_amount

I am required to write a query which gives the employee details, the number of times an employee has received a salary increase, the value of the maximum increase amount and the date of that increase. Here is what i have so far:

我需要编写一个查询，其中给出了员工的详细信息，员工获得加薪的次数，最大增加金额的值以及增加的日期。这是我到目前为止：

SELECT e.*, count(i.inc_amount), max(i.inc_amount)
FROM salary_increase AS i
RIGHT JOIN emp_table AS e
ON i.emp_id=e.emp_id
GROUP BY e.emp_id;

this correctly gives all the requirements apart from the date on which the maximum increase was awarded. I have tried the following with no success:

这正确地给出了除了授予最大增加的日期之外的所有要求。我试过以下但没有成功：

SELECT e.*, count(i.inc_amount), max(inc_amount), t.inc_date
FROM salary_increase AS i
RIGHT JOIN emp_table AS e
ON i.emp_id=e.emp_id
RIGHT JOIN
    (
    SELECT emp_id, inc_date FROM salary_increase
    WHERE inc_amount=max(inc_amount) GROUP BY emp_id
    ) AS t
ON e.emp_id=t.emp_id
GROUP BY e.emp_id;

this gives an error 'Invalid use of group function'. Does anyone know what i'm doing wrong?

这会给出错误“组功能的无效使用”。有谁知道我做错了什么？

1 个解决方案

#1

You can't do this WHERE inc_amount=max(inc_amount) in the where clause, either use HAVING or do it in the condition of join, try this instead:

你不能在where子句中执行WHERE inc_amount = max（inc_amount），要么使用HAVING要么在连接条件下执行，请尝试这样做：

SELECT 
  e.emp_id, 
  e.inc_date,
  t.TotalInc, 
  t.MaxIncAmount
FROM salary_increase AS i
INNER JOIN emp_table AS e ON i.emp_id=e.emp_id
INNER JOIN
(
   SELECT 
     emp_id,
     MAX(inc_amount)     AS MaxIncAmount, 
     COUNT(i.inc_amount) AS TotalInc
   FROM salary_increase
   GROUP BY emp_id
) AS t ON e.emp_id = t.emp_id AND e.inc_amount = t.MaxIncAmount;