SQL is a theoretical language

SQL that allows a high-level expression of queries.

relational algebra is

Relational algebra in DBMS is a procedural query language, which describes the procedure to obtain the result.

Queries in relational algebra are performed using operators

What is the purpose of the SELECT operation in relational algebra?

Relational Algebra the basic set of operations for relational model

Relational algebra is describes the order of operations in the query

Relational algebra expression the sequence of operations in a relation algebra.

SELECT Operation

What is the result of the SELECT operation in relational algebra?

The SELECT operation in relational algebra is denoted by:

SELECT operator is Binary

degree of the relation resulting from a SELECT operation its number of attributes is the less than the degree of R

number of tuples in the resulting relation is always less than or equal to the number of tuples in R.

|σc (R)| ≤ |R| for any condition C.

The SELECT operation isn't commutative

PROJECT operation selects certain columns from the table and discards the other columns.

The Project operation in relational algebra is denoted by:

π <list1> (π <list2>)(R)) =π<list1>(R) as long as <list2> contains the attributes in <list1>

commutativity does not hold on PROJECT