# Degenerate Dimension

Generally, what is a Dimension table? Something like a master list. Employee, Product, Date, Store.

In a data warehouse, a degenerate dimension is a dimension key in the fact table that does not have its dimension table.

_It is key in the fact table but does not have its dimension table._



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Degenerate dimensions are most familiar with the transaction and accumulating snapshot fact tables.

Means no separate Dimension table.&#x20;

OrderNo is degenerate dimension. As it has no Dimension table.



### Uses of using Degenerate Dimension Table

```
- Grouping line items
- Getting the average sale
- Tracking
```



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### Other Examples of Degenerate Dimensions are

1. **Order number or invoice number**: This is a typical example of a degenerate dimension. It is a unique identifier for an order or an invoice but has no meaningful attributes other than its value. This degenerate dimension can be used in a fact table to analyze sales by order or invoice number.
2. **Tracking number**: Another example of a degenerate dimension is a tracking number for a shipment. Like an order number, it is a unique identifier but has no additional attributes associated with it. It can be used in a fact table to analyze shipping performance or delivery times.
3. **ATM transaction number**: In banking, an ATM transaction number is a unique identifier for a transaction at an ATM. It can be used in a fact table to analyze ATM usage patterns and trends.
4. **Serial number**: A serial number is a unique identifier assigned to a product or equipment. It can be used in a fact table to analyze the performance of a particular product or equipment.
5. **Coupon code**: A coupon code is a unique identifier to redeem a discount or promotion. It can be used in a fact table to analyze the usage and effectiveness of different marketing campaigns or promotions.

Degenerate dimensions are helpful when we have a unique identifier for an event or transaction. Still, it has no additional attributes that make it sound like a separate dimension table. In these cases, we can include the unique identifier in the fact table as a degenerate dimension.
