normally we require 3 tables for IS-A relationship

if covering constraint is there (if both Engineer and Manager collectively represent whole employees ) then only 2 tables are sufficient. which are one for engineer and another for manager and same logic apply further

Let E1 and E2 be two entities and R is a relation between E1 and E2, then what is the minimum no of tables required to represent E1, E2 and R if - E1 and E2 have 1:m cardinality(E1 on 1 side, E2 on m side); E1 has total participation and E2 has partial ... . E1 and E2 have m:n cardinality; both E1 and E2 have total participation. I am not able to find a single solution for this. Kindly help.

In case of 1:1 relationships, when can we have a minimum of 1 table? when both the entities have total participation when atleast one entity have total participation