RENAME operation which can rename either the relation name or the attribute names, or both is a unary operator

ρS(R)

ρ(B1, B2, ..., Bn)(R)

ρS(B1, B2, ..., Bn)(R)

Renaming in SQL is accomplished by using

Relational set operators are used to combine or subtract the records from two tables

RELATIONAL SET OPERATORS is

RELATIONAL SET OPERATORS are used for doing set operations on relations having same schema.

...... , is a relation that includes all tuples that are either in R or in S or in both R and S. Duplicate tuples are eliminated

In order to set operators to work in database, it should have same number of columns participating in the query and the datatypes of respective columns should be same is called Union Compatibility.

IN UNION Duplicate tuples are allowed.

is a relation that includes all tuples that are in both R and S.

is a relation that includes all tuples that are in R but not in S.

R ∪ S ≠ S ∪ R

R − S ≠ S – R

The set operations ∪ and ∩ are ……………… but “–” is not.

If the cardinality of R, S and R∩S is 40, 50, and 20 respectively, then the cardinality of R∪S is 70.

R ∪ (S ∪ T) = (R ∪ S) ∪ T and (R ∩ S ) ∩ T = R ∩ (S ∩ T )

R ∩ S = ((R ∪ S ) − (R − S )) − (S − R)

For the Cartesian product to be defined, the two relations involved must have disjoint headers—that is, they must not have a common attribute name

CARTESIAN PRODUCT operation applied by itself is generally meaningful .