SQL Left join

/*

 

You are given two tables, department and employee, with the following structure:

 

  create table department (

      dept_id integer not null,

      dept_name varchar(30) not null,

      dept_location varchar(30) not null,

      unique(dept_id)

  );

 

  create table employee (

      emp_id integer not null,

      emp_name varchar(50) not null,

      dept_id integer not null,

      salary integer not null,

      unique(emp_id)

  );

 

Each record in the table department represents a department which might hire some employees. Each record in the table employee represents an employee who works for one of the departments from the table department. The salary of each employee is known. (However, the locations of the departments are not relevant here.)

 

Write an SQL query that returns a table comprising all the departments (dept_id) in the table department that hire at least one employee, the number of people they employ and the sum of salaries in each department. The table should be ordered by dept_id (in increasing order).

 

For example, for:

 

  department:

 

   dept_id | dept_name  | dept_location

  ---------+------------+---------------

   10      | Accounts   | Delhi

   20      | Marketing  | Delhi

   40      | IT         | Warsaw

   30      | Production | Hyderabad

   50      | Sales      | Bengaluru

 

 

  employee:

 

   emp_id | emp_name    | dept_id | salary

  --------+-------------+---------+--------

   1      | Jojo        | 20      | 5000

   2      | Popat Lal   | 30      | 15000

   3      | Santa Singh | 40      | 25000

   4      | Banta Singh | 20      | 7500

   5      | Sohan Lal   | 20      | 15000

   6      | Kk          | 10      | 12000

   7      | Bob         | 20      | 35000

   8      | John        | 30      | 25000

   9      | Smith       | 40      | 5000

 

your query should return:

 

   dept_id | count | sum_of_salary

  ---------+-------+---------------

   10      | 1     | 12000

   20      | 4     | 62500

   30      | 2     | 40000

   40      | 2     | 30000

 

*/

 

-- write your code in SQLite 3.8.6

SELECT 

    department.dept_id,

    COUNT(employee.dept_id) AS 'count', 

    SUM(employee.salary) AS 'sum_of_salary' 

FROM employee LEFT JOIN department

    ON employee.dept_id=department.dept_id

GROUP BY department.dept_id

ORDER BY department.dept_id;