NULL Values

Unfortunately, working with data is an easy way to see that we don’t live in a perfect world. There are more than a few instances of there not being any data available to display, which can cause all sorts of issues with our queries. These values are what we call NULLS*, and can differ depending on your situation.

Most often at the start, we can leave them as NULL. However, depending on the structure of your table, you could do a 0, or even an empty text string.

We can search or avoid NULL values by using the IS NULL or IS NOT NULL when using our WHERE clause.

SELECT column, another_column
FROM mytable
WHERE column IS/IS NOT NULL
AND/OR condition...

Next: Lesson 9