I'm trying to build database which allow me store job postings from scraped websites and now I'm in phase of creating a relational model. Getting straight to the point I want to know how should I re-design my relational model if I know one of my linking table's column (
FK3 level_id) will contain NULLs. And the model:
Every job posting has title and source website (
Sometimes job posting contains information about additional skills. Their names I store in
Additional skillmay be required or may be not required (
Additional skill may or may not contain information about its level (I store level names in
Because job posting may contain information about 0 or 1 or many additonal skills and each one of them may have its own level I associated everything in linking table (
Overall_required_level linking table is not important in this question.
Because we know that job posting may contain several
Additional skill and not every
Additonal skill may contain information about its own
Level so there will be nulls in
level_id column in
Additional_skill-Level-Jobs linking table. To be honest they are not as bad as they look but I'd like to know how could I improve my relational model if I know with certainty that one of the column will be having NULLs.