How to SUM only certain rows of a column, save to variables, other misc.

I'm on MySQL 8.0 and using MySQL Workbench. I just started to learn MySQL and I'm having a lot of trouble figuring out how to do this.

I have a table called 'business_ledger' and the following fields: employee_name (various string values to denote employees - not used in this query but it's part of the database), title (with values: Novice, Journeyman, Master), Earnings (various int values), certification (with values: None, In Progress, Certified), and percent (this will be created later)....

How to SUM only certain rows of a column, save to variables, other misc.

from MySQL https://ift.tt/2XcWsAT
via IFTTT