# Rollup

The **Rollup** function aggregates and looks up data in a second workbook data element.

### Syntax

```
Rollup(formula, local key 1, external key 1, [local key 2], [external key 2], ...)
```

Function arguments:

* **formula** (required) - The formula to compute (or the target column to reference) for the row in the target element.
* **local key 1** (required) - The column to use as a join key in the local data element.
* **external key 1** (required) - The column to use as a join key in the target data element.
* **local key 2 +** (optional) - An additional column to use as a join key in the local data element.
* **external key 2 +** (optional) - An additional to use as a join key in the target data element.

### Example

```
Rollup(Sum([Sales Amounts/Sales Amount]), [Order Number], [Sales Amounts/Order Number])
```

Data is inserted into the *Orders* table’s **\[Calc]** column from *Sales Amount* table’s **\[Sales Amount]** column.

The function’s *formula* parameter uses the Sum function to aggregate values from the *Sales Amount* table’s **\[Sales Amount]** column.

These two tables are joined using a single set of join keys: *Orders’* **\[Order Number]** column is joined with *Sales Amounts’* **\[Order Number]** column.

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