I'm very new at my sql and I have the following problem:
I'm building a grammar website and I have amongst other things one table that stores details about each grammar module (name, number of exercises, description), one table called exercises that defines each exercises (code, which grammar module they belong to, level...) and one table that stores the marks (exercise code, mark, date...).
I want to query the database so that only the marks for a particular grammar module appears.
I've tried the following in mysql:
select exercisecode,marks from marks where exercisecode=(select code from exercises where grammarmodule='de');