I would be happy to ask my first question on StackOverflow.  

I have two tables (employees and salaries) within my database (employees).  

Employees table looks like this:

```
+------------+---------------+------+-----+---------+-------+
| Field      | Type          | Null | Key | Default | Extra |
+------------+---------------+------+-----+---------+-------+
| emp_no     | int           | NO   | PRI | NULL    |       |
| first_name | varchar(14)   | NO   |     | NULL    |       |
| last_name  | varchar(16)   | NO   |     | NULL    |       |
+------------+---------------+------+-----+---------+-------+

```

Salaries table looks like this:

```
+-----------+------+------+-----+---------+-------+
| Field     | Type | Null | Key | Default | Extra |
+-----------+------+------+-----+---------+-------+
| emp_no    | int  | NO   | PRI | NULL    |       |
| salary    | int  | NO   |     | NULL    |       |
| from_date | date | NO   | PRI | NULL    |       |
| to_date   | date | NO   |     | NULL    |       |
+-----------+------+------+-----+---------+-------+

```

I want to return values for a specific date interval. For instance, I want to know what salary an employee had for an interval in a dynamic view, for the 1990-1991 years for 1991-1992 years, etc.

I wrote the following query: 

```
SELECT 
    e.emp_no,
    e.first_name,
    e.last_name,
    s.salary AS Salary_for_1990
FROM
    employees e
        JOIN
    salaries s ON e.emp_no = s.emp_no
WHERE
    from_date BETWEEN '1990-01-01' AND '1990-12-31'
GROUP BY e.emp_no
ORDER BY e.emp_no ASC
LIMIT 10;

```

I got the following result:

```
+--------+------------+-----------+-----------------+
| emp_no | first_name | last_name | Salary_for_1990 |
+--------+------------+-----------+-----------------+
|  10001 | Georgi     | Facello   |           66961 |
|  10004 | Christian  | Koblick   |           48271 |
|  10005 | Kyoichi    | Maliniak  |           82621 |
|  10006 | Anneke     | Preusig   |           40000 |
|  10007 | Tzvetan    | Zielinski |           60740 |
|  10009 | Sumant     | Peace     |           70889 |
|  10011 | Mary       | Sluis     |           42365 |
|  10013 | Eberhardt  | Terkki    |           46305 |
|  10018 | Kazuhide   | Peha      |           61648 |
|  10021 | Ramzi      | Erde      |           59700 |
+--------+------------+-----------+-----------------+ 

```

So it works for a single value '1990-1991' years, however, **I seek for a possibility to add in the query additional column for '1991-1992', '1992-1993' years, etc** to be able to see the dynamic growth of employee's salaries.  

I thought about variables, however, I don't have an idea how to query it within the context.  

Look forward to your answers.  
 Thank you in advance.