SQL Query in c#

Question

I might have a problem with my SQL query. In this query I\'m combining 4 different tables.

• I have a table courses where general information is stor

Answer 1

Courses the employee hasn't taken.

SELECT * FROM courses
WHERE course_number IN (
    SELECT course_id FROM job_course
    WHERE course_id NOT IN (
        SELECT course_id FROM emp_courses
        WHERE emp_id = {someid}
    ) AND job_id = (
        SELECT job_id FROM employees
        WHERE emp_id = {user_input}
    )
)

Which employees still need to take a course.

SELECT emp_name FROM employees
WHERE emp_id NOT IN (
    SELECT emp_id FROM emp_courses
    WHERE course_id = {user_input}
)

Variant of above.

SELECT emp_name FROM employees
WHERE emp_id NOT IN (
    SELECT emp_id FROM emp_courses
    WHERE course_id = (
        SELECT course_id FROM courses
        WHERE course_number = {user_input}
    )
)