What is the difference between Select and Project Operations

Question

I\'m referring to the basic relational algebra operators here.
As I see it, everything that can be done with project can be done with select.

I don\'t know if

Answer 1

In Relational algebra 'Selection' and 'Projection' are different operations, but the SQL SELECT combines these operations in a single statement.

Select retrieves the tuples (rows) in a relation (table) for which the condition in 'predicate' section (WHERE clause) stands true.

Project retrieves the attributes (columns) specified.

The following SQL SELECT query:

select field1,field2 from table1 where field1 = 'Value';

is a combination of both Projection and Selection operations of relational algebra.