What is the syntax for using the next_day function in Databricks SQL and Databricks Runtime, and what arguments does it take?
The syntax for using the `next_day` function in Databricks SQL and Databricks Runtime is as follows:

`next_day(expr, dayOfWeek)`

The `next_day` function takes two arguments:

* `expr`: A DATE expression.
* `dayOfWeek`: A STRING expression identifying a day of the week.

The `dayOfWeek` argument must be one of the following (case insensitive): 'SU', 'SUN', 'SUNDAY', 'MO', 'MON', 'MONDAY', 'TU', 'TUE', 'TUESDAY', 'WE', 'WED', 'WEDNESDAY', 'TH', 'THU', 'THURSDAY', 'FR', 'FRI', 'FRIDAY', 'SA', 'SAT', 'SATURDAY'.

The function returns the first date which is later than `expr` and named as in `dayOfWeek`. In Databricks Runtime, if `spark.sql.ansi.enabled` is false, the function returns NULL instead of an error for a malformed `dayOfWeek`.