***Numerical Types** (Integer, Float, DoubleFloat, Decimal, etc) - These fields store numbers. Integers are whole numbers; Floats and Decimals are ways to store numbers with decimals in them. Numerical types store things like age, bank account balances, costs, latitudes, and longitudes, to name a few.
***Time Types** (Timestamp, etc) - These fields are a special format of a number used to store dates and times (or both). Sometimes databases store an integer timestamp which is either seconds or milliseconds, such as `00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970`. This convention allows for compact storage of timestamps.
***IDs** (Also called **primary keys**) - This field uniquely identifies each row. For example, imagine a car reservation app where you can book a car in advance. The ID could be the customer's username.
***IDs** (Also called **primary keys**) - This field uniquely identifies each row. For example, imagine a car reservation app where you can book a car in advance. The ID of the reservation could be the reservation number (no two reservations would share the same reservation number, making the ID unique).
**Customer**
| ID | Name| Age |
| ---- | --- |
| ---- | --- | --- |
| 11| John | 25 |
| 12| Jenny | 31 |
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@@ -62,14 +62,14 @@ For example, in our hypothetical car booking app, we could connect each reservat
