Write a query to display unique 12th hour reading present in the electricity_reading table. Display the records sorted in descending order based on h12.

To retrieve unique 12th hour readings from the electricity_reading table and sort them in descending order based on h12, you can use the following SQL query:

SELECT DISTINCT h12
FROM electricity_reading
WHERE h12 IS NOT NULL
ORDER BY h12 DESC;

Explanation of the Query:

1. SELECT DISTINCT h12: This clause selects unique values from the h12 column.
2. FROM electricity_reading: Specifies the table from which to retrieve the data.
3. WHERE h12 IS NOT NULL: This condition ensures that only non-null readings are considered, as null values would not be meaningful in this context.
4. ORDER BY h12 DESC: This orders the unique 12th hour readings in descending order.

Final Result

Executing this query will provide a list of unique 12th hour readings sorted from the highest to the lowest value.