This module concentrates on providing an expressive, concise way to
declare SQL expressions by exporting carefully-designed functions. It is
possible to use the module to generate SQL query conditions and pass
them as arguments to other more versatile query builders such as
SQL::Maker.

The functions exported by the module instantiate comparator objects that
build SQL expressions when their "as_sql" method are being invoked.
There are two ways to specify the names of the columns to the
comparator; to pass in the names as argument or to specify then as an
argument to the "as_sql" method.