Some questions arises when using MAGMI generic SQL datasource. Magmi 0.7.18 displays the following input information when using that plugin:
by dweeves:
Your SELECT has to be put in a .sql file in the directory listed in red. (name it as you want as long as it ends with .sql extension)
The "Initial Statements" is a field that is meant to hold the "connection" time statements (like SET NAMES 'UTF8').
For the "quick count" , you might also add a .sql.count file in the same dir with the same name that the request you want to achieve.
By default magmi will find the count using a
SELECT COUNT(*) FROM (your request here)
see Generic SQL Datasource plugin documentation.