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 Title IN ('Manager', 'Staff');
or to list those earning 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 all NOT's are performed before any AND's or OR's.
