This SQL query retrieves a list of unique first names...

This SQL query retrieves a list of unique first names from the patients table that appear exactly once (i.e., first names that are not repeated in the table). The query also sorts the results in ascending order of the first_name. Here's a breakdown:

1. SELECT first_name: Specifies that the query is selecting the first_name column from the patients table.

2. FROM patients: Indicates that the data is being queried from the patients table.

3. GROUP BY first_name: Groups the rows in the table by the values in the first_name column. This means all rows with the same first_name are grouped together.

4. HAVING COUNT(*) = 1: Filters the groups to include only those that have exactly one row (i.e., first_name values that appear only once in the table).

5. ORDER BY first_name: Sorts the resulting first_name values in ascending order.

Result:

The output will be a sorted list of first names from the patients table where each first name is unique and appears only once in the table.