Here is another fancy way of dealing with NULLs if you have some equations you have to run.
Let's say that you work for an organization that deals with different salary types:
COALECE allows you to specify a comma delimited list of expressions and it will return the first non-NULL expression. So, in our example above, we have columns that show an employee's: hourly wage, salary, commission amount and number of sales. We can then specify each expression with the wage calculation, as seen below:
SELECT COALESCE(hourly_wage * 40 * 52, salary, commission * salesnum) AS 'Total Salary'
This will then return the wage for each employee, no matter if they are hourly, salary or commission based.