Trying to write a query that correctly creates and populates an ID column that counts until it encounters a new non-null value in the Data column, at which point it restarts at 1. Here’s an example of the data.

Trying to write a query that correctly creates and populates an ID column that counts until it encounters a new non-null value in the Data column, at which point it restarts at 1. Here’s an example of the data.