% This is generated by ESQL's AbstractFunctionTestCase. Do not edit it. See ../README.md for how to regenerate it.

**Parameters**

`datePattern`
:   The date format. Refer to the [`DateTimeFormatter` documentation](https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/time/format/DateTimeFormatter.html) for the syntax. If `null`, the function returns `null`.

`dateString`
:   Date expression as a string. If `null` or an empty string, the function returns `null`.