Module 3: Filtering data with WHERE and NULL values

Let’s see how NULL values and time zones change the rows we get from a WHERE clause.

We use WHERE to choose which rows we want from a table. It is one of the first SQL clauses we learn, but the rows we get still depend on how we write the condition. For example, order_status <> 'canceled’ removes canceled orders. It also removes orders whose status is NULL, even though we didn’t ask it to.

In this module, we’ll try that filter and see why the missing statuses disappear. After that, we’ll use WHERE to find orders from one day in São Paulo when the timestamps are stored in UTC.

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