What are the basic operations of relational algebra in relational databases

Basic relational algebra operations: selection, projection, concatenation, set difference, Cartesian product and renaming operations, of which selection, projection and renaming are unary operations, and the other three operate on two relations, so they are binary operations;

Additional relational algebra operations: set intersection ∩, natural join operations, assignment operations, outer join operations (left outer join, right outer join, full outer join);< /p>

Extended relational algebra operations: generalized projection, aggregation (common aggregation functions: sum, avg, min, max).