# Example: Customers Data Structure

This document provides examples of the data structures and schemas used in the `customers` domain.

## Schema: `dim_customers`

| Column        | Type   | Description                                      |
|:--------------|:-------|:-------------------------------------------------|
| `customer_id` | STRING | Unique identifier for each customer.             |
| `first_name`  | STRING | Customer first name.                             |
| `last_name`   | STRING | Customer last name.                              |
| `email`       | STRING | Primary contact email address.                   |
| `signup_date` | DATE   | Date the customer created their account.         |
| `tier`        | STRING | Customer loyalty tier: `FREE`, `SILVER`, `GOLD`. |

## Common Queries

### Active Customers

Customers who have placed at least one order in the last 30 days.

```sql
SELECT DISTINCT c.customer_id
FROM dim_customers c
JOIN fact_orders o ON c.customer_id = o.customer_id
WHERE o.order_timestamp > CURRENT_DATE - INTERVAL '30 days'
```
