Table schema:
CREATE TABLE employees (email VARCHAR, department_id VARCHAR, commission_pct VARCHAR, salary VARCHAR)

Question: 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.
SQL: SELECT email FROM employees WHERE commission_pct = "null" AND salary BETWEEN 7000 AND 12000 AND department_id = 50