display the emails of the employees who have no commission percentage and salary within the range 7000 to 12000 and works in that department which number is 50.
SELECT email FROM employees WHERE commission_pct = "null" AND salary BETWEEN 7000 AND 12000 AND department_id = 50
``` yaml
employees: # name of dataframe
- EMPLOYEE_ID:
    dtype: int64
    sample_values: 100, 101, 102
- FIRST_NAME:
    dtype: string
    sample_values: Steven, Neena, Lex
- LAST_NAME:
    dtype: string
    sample_values: King, Kochhar, De Haan
- EMAIL:
    dtype: string
    sample_values: SKING, NKOCHHAR, LDEHAAN
- PHONE_NUMBER:
    dtype: string
    sample_values: 515.123.4567, 515.123.4568, 515.123.4569
- HIRE_DATE:
    dtype: datetime
    sample_values: 1987-06-17, 1987-06-18, 1987-06-19
- JOB_ID:
    dtype: string
    sample_values: AD_PRES, AD_VP, AD_VP
- SALARY:
    dtype: int64
    sample_values: 24000, 17000, 17000
- COMMISSION_PCT:
    dtype: float64
    sample_values: 0.0, 0.0, 0.0
- MANAGER_ID:
    dtype: int64
    sample_values: 0, 100, 100
- DEPARTMENT_ID:
    dtype: int64
    sample_values: 90, 90, 90

```
EMAIL
