PROJECT degree ........... the number of attributes in < attribute list >.

The number of tuples in a relation resulting from a PROJECT operation is always less than or equal to the number of tuples in R.

In SQL, the PROJECT attribute list is specified in the SELECT clause of a query

commutativity does hold on PROJECT .

Renaming in SQL is accomplished by using ...

Relational set operators are used to combine or subtract the records from two tables, so they are also binary set operators

They are used for doing set operations on relations having different schema

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

SET DIFFERENCE : The result of this operation, denoted by R – S, is a relation that includes all tuples that are in S but not in R .

INTERSECTION: The result of this operation, denoted by R ∩ S, is a relation that includes all tuples that are in both R and S.

The MINUS operation is commutative

UNION and INTERSECTION are commutative operations

The CARTESIAN PRODUCT operation—also known as CROSS PRODUCT or CROSS JOIN—which is denoted by ×

For the Cartesian product to be defined, the two relations involved must have disjoint headers—that is, they must have a common attribute name.

is used to combine related tuples from two relations into single “longer” tuples

The JOIN operation can be specified as aCARTESIAN PRODUCT operation followed by a PROJECT operation

A general join condition is of the form <condition> AND <condition> AND...AND <condition>

The general form is R÷ S to apply this operation the relation S must not be subset of Relation R.

An intuitive property of the division operator of the relational algebra is simply that it is the inverse of the Cartesian product.

There are two levels at which we can discuss the goodness of relation schemas