Write a query to change the owner_name  'Nicholas' to 'Alexander' present in the building table.

Sure, here is the SQL query to update the owner_name from 'Nicholas' to 'Alexander' in the building table:

UPDATE building
SET owner_name = 'Alexander'
WHERE owner_name = 'Nicholas';

Here's a step-by-step breakdown of the query:

1. UPDATE building: This line is telling SQL that we want to update the table named 'building'.

2. SET owner_name = 'Alexander': This line is specifying what change we want to make. In this case, we want to change the 'owner_name' to 'Alexander'.

3. WHERE owner_name = 'Nicholas': This line is specifying the condition that must be met for the row to be updated. In this case, we only want to update rows where the 'owner_name' is currently 'Nicholas'.