# caseWhen

Returns values depending on boolean expressions. This function can only be used in an [ingestion transformation function](https://docs.pinot.apache.org/release-1.0.0/for-developers/advanced/ingestion-level-transformations).

## Signature

> caseWhen(booleanExpr1, valueIfExpr1True, booleanExpr2, valueIfExpr2True) caseWhen(booleanExpr1, valueIfExpr1True, booleanExpr2, valueIfExpr2True, ... ,valueIfFalse)

| Arguments                              | Description          |
| -------------------------------------- | -------------------- |
| `booleanExpr1`                         | A boolean expression |
| `valueIfExpr1True`, `valueIfExpr2True` | A value to return.   |

## Usage Examples

The usage examples are based on extracting fields from the following JSON documents:

```json
{
  "latitude": 1.0
}
```

| Expression                                 | Value   |
| ------------------------------------------ | ------- |
| `CASEWHEN(latitude > 0, 'North', 'South')` | `North` |
| `CASEWHEN(latitude > 0, 1, 0)`             | `1`     |

This function can be used in the [table config](https://docs.pinot.apache.org/release-1.0.0/configuration-reference/table) to add `northernHemisphere` column:

```json
{
   "tableConfig":{
      "ingestionConfig":{
         "transformConfigs":[
            {
               "columnName":"northernHemisphereStr",
               "transformFunction":"CASEWHEN(latitude > 0, 'North', 'South')"
            }
         ]
      }
   }
}
```