How often I use
I use SQL at least a few times a week.
My skills with SQL
I first learned SQL in graduate school for a course on database design and then first used it for a project the following semester when I had to build a PHP site backed by a MySQL database. Now, I use Microsoft SQL Server and SSMS at work. I am the primary database support developer, which means that I help other devs set up their own development or testing databases, I deploy schema changes to all environments, I help sync data between dev/stage/production environments, and I stand up ETL and replication for our production databases.
I can write queries of medium complexity without looking up anything, but complex queries require a little research. I have written stored procedures and views of varying complexity--from simple joins to unions, cross apply, and merges. And I've written some functions and triggers, too.