Table: Project
+-------------+---------+
+| Column Name | Type |
++-------------+---------+
+| project_id | int |
+| employee_id | int |
++-------------+---------+
+(project_id, employee_id) is the primary key of this table.
+employee_id is a foreign key to Employee table.
+Each row of this table indicates that the employee with employee_id is working on the project with project_id.
+
+
++ +
Table: Employee
+------------------+---------+ +| Column Name | Type | ++------------------+---------+ +| employee_id | int | +| name | varchar | +| experience_years | int | ++------------------+---------+ +employee_id is the primary key of this table. It's guaranteed that experience_years is not NULL. +Each row of this table contains information about one employee. ++ +
+ +
Write an SQL query that reports the average experience years of all the employees for each project, rounded to 2 digits.
+ +Return the result table in any order.
+ +The query result format is in the following example.
+ ++
Example 1:
+ +Input: +Project table: ++-------------+-------------+ +| project_id | employee_id | ++-------------+-------------+ +| 1 | 1 | +| 1 | 2 | +| 1 | 3 | +| 2 | 1 | +| 2 | 4 | ++-------------+-------------+ +Employee table: ++-------------+--------+------------------+ +| employee_id | name | experience_years | ++-------------+--------+------------------+ +| 1 | Khaled | 3 | +| 2 | Ali | 2 | +| 3 | John | 1 | +| 4 | Doe | 2 | ++-------------+--------+------------------+ +Output: ++-------------+---------------+ +| project_id | average_years | ++-------------+---------------+ +| 1 | 2.00 | +| 2 | 2.50 | ++-------------+---------------+ +Explanation: The average experience years for the first project is (3 + 2 + 1) / 3 = 2.00 and for the second project is (3 + 2) / 2 = 2.50 ++