Write a query to display the number of buildings having an email_address. Give an alias name as 'count_of_buildings_with_email'.

Sure, here is a SQL query that will give you the number of buildings that have an email address. I'm assuming that your table name is 'buildings' and the column for email addresses is 'email_address'.

SELECT COUNT(*) AS count_of_buildings_with_email
FROM buildings
WHERE email_address IS NOT NULL;

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

1. SELECT COUNT(*) AS count_of_buildings_with_email: This part of the query is used to count the number of rows in the 'buildings' table where the 'email_address' is not null. The AS keyword is used to give this count a name, or alias, 'count_of_buildings_with_email'.

2. FROM buildings: This part of the query specifies the table we are selecting data from, which is the 'buildings' table.

3. WHERE email_address IS NOT NULL: This is the condition for the query. It only counts the rows where the 'email_address' column is not null, meaning there is an email address for the building.