In the entity-relationship model, a table line compares to an element occurrence. The presence of a compulsory relationship shows that the base cardinality is 0 or 1 for the required element. the presence of a[n] optional entity shows that its base cardinality is zero.An entity-relationship model (or ER model) portrays interrelated things of excitement for a specific zone of data. A crucial ER model is made out of substance types (which portray the things of interest) and decides associations that can exist between components (events of those component types).