Union Compatible Relation (Relational Algebra)

relational-algebra

Definition

Union Compatible Relation (Relational Algebra)

Two relations $R_1,R_2$ are called union compatible if:

1. they have the same number of attributes, and
2. the domain of each attribute in column order is the same in both relations

Union compatibility is normally achieved using projection, i.e.:

$${\pi }_{name}(students)\cup {\pi }_{name}(teachers)$$