# Discount by customer tier (DMN)

The simplest useful decision table: a discount that depends on tier and order value. Unique as the hit policy means overlapping rules become a visible error.

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## What this example shows

* Two input columns and one output.
* FEEL ranges rather than a row per value.
* A Unique hit policy, so overlap cannot pass silently.

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## Columns

| **Column**          | **Type and meaning**           |
| ------------------- | ------------------------------ |
| Tier (input)        | string: bronze, silver or gold |
| Order value (input) | number: the order total        |
| Discount (output)   | number: percentage applied     |

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## The decision table

Hit policy: **U (Unique)**. Cells are FEEL expressions, so a range, a list or a negation is a legal value; a dash means the input is irrelevant to that rule.

| **Tier** | **Order value** | **Discount %** | **Notes**                       |
| -------- | --------------- | -------------- | ------------------------------- |
| "bronze" | < 500           | 0              | No discount below the threshold |
| "bronze" | \[500..2000)    | 2              |                                 |
| "bronze" | \>= 2000        | 5              |                                 |
| "silver" | < 500           | 2              |                                 |
| "silver" | \[500..2000)    | 5              |                                 |
| "silver" | \>= 2000        | 8              |                                 |
| "gold"   | < 2000          | 8              |                                 |
| "gold"   | \>= 2000        | 12             | Capped by policy at 12          |

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## Making it your own

* Add a third input for promotional codes rather than duplicating every row.
* Set allowed values on the tier column so a typo becomes an error.
* If the table grows past about twenty rows, split the decision in two.

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## Related

[Loan eligibility (DMN)First hit policy, because the rules are ordered.](https://help.gocapable.com/diagrams/loan-eligibility-dmn.html)

[Shipping cost (DMN)Weight bands and destination zones.](https://help.gocapable.com/diagrams/shipping-cost-dmn.html)

[DMN examplesBack to the rest of these examples.](https://help.gocapable.com/diagrams/dmn-examples.html)

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_The hit policy is the whole decision._