I had question about what would be returned from this query
SELECT `name` FROM `customer` WHERE `date` <> '05/05/10'
Here was the table:
John Smith | null |
Mary Smith | 05/05/10 |
Joe Allen | 02/16/10 |
I had to take a pause at that. I had no idea if John Smith would be returned.
Turns out that NULL is never *equal* to another value.
It is also never *not equal* to another value.
NULL is basically like "I have no idea" when it comes to comparisons.
The way to return both John Smith and Joe Allen would be
```
SELECT `name` FROM `customer` WHERE `date` <> '05/05/10' OR `date` IS NOT NULL
```
[Source](http://stackoverflow.com/questions/26554462/why-does-my-sql-query-some-value-not-return-any-rows-where-null)
[Source](https://dev.mysql.com/doc/refman/5.7/en/working-with-null.html)