Another SQL session in the books
therealbrandonwilson • 23 Jul 2021 •
Today I delivered Session 6 of my SQL course for my client. This session covered advanced functions and statements used in the SELECT and WHERE statements.
When I had originally conceived the course, I had all these goodies packed within the SELECT and WHERE sessions. The problem is that the information was too overwhelming in the beta run. I decided to pull out the less common but still valuable advanced functions and put them into a separate lesson delivered later in the course. The content and timeline works out a lot better this way.
One of my favorite statements I discussed today is EXISTS and NOT EXISTS. This one is extremely powerful and opens up all kinds of options that are not available with standard functions in a WHERE statement. An EXIST statement creates a subquery that is evaluated and returns records based on whether they meet or do not meet the criteria in the subquery. I used examples to show the results when you use a parameter in the WHERE statement vs using the same parameter in an EXISTS statement.
If you can master the EXISTS statement in SQL, you are well on your way to becoming a seasoned SQL person.
Comments
Learned something new today - never used EXISTS before! Only ever SELECT
EXISTS is definitely one of my favorites.
:) I use SQL very often and used EXIST a handful of times. I think this process of teaching and creating a course is a wonderful way to enforce your knowledge. Great progress Brandon.