1⟩ What is complex join? Difference with Foreign key Primary Key join?
Complex joins are joins which have following diffrences from a PK-FK joins
# Complex joins can have conditional mappings like >,<,>=,NOT,AND,etc apart from '=' whereas the PK-FK joins are always '='.
# PK-FK joins are always (1-N), whereas complex joins can have (1 - 0,1) and (0,1 - N) kind of relationships