Data Types, Missing Values, and Safe Filtering

About 70-90 minutes of guided work.

By the end of this module you can predict how NULL behaves in a filter, an aggregate, and a join; decide deliberately whether a missing value means zero or unknown; and report the denominator you actually measured.

Units

1. Unit 03.00: Types, casting, and the text-date trap
2. Unit 03.01: Three-valued logic: TRUE, FALSE, and UNKNOWN
3. Unit 03.02: Why aggregates skip NULL and reports mislead
4. Unit 03.03: COALESCE: when zero is a decision, not a default
5. Unit 03.04: Reporting the denominator you actually measured

Module work

• Activity
• Knowledge check
• Summary