An easier method of using compound conditions uses IN or BETWEEN. For example, if you wanted to list all managers and staff:

SELECT EMPLOYEEIDNO
FROM EMPLOYEESTATISTICSTABLE
WHERE POSITION IN ('Manager', 'Staff');

or to list those making greater than or equal to $30,000, but less than or equal to $50,000, use:

SELECT EMPLOYEEIDNO
FROM EMPLOYEESTATISTICSTABLE
WHERE SALARY BETWEEN 30000 AND 50000;

To list everyone not in this range, try:

SELECT EMPLOYEEIDNO
FROM EMPLOYEESTATISTICSTABLE
WHERE SALARY NOT BETWEEN 30000 AND 50000;

Similarly, NOT IN lists all rows excluded from the IN list.

Additionally, NOT's can be thrown in with AND's & OR's, except that NOT is a unary operator (evaluates one condition, reversing its value, whereas, AND's & OR's evaluate two conditions), and that all NOT's are performed before any AND's or OR's.

SQL Order of Logical Operations (each operates from left to right)

1. NOT
2. AND
3. OR