Give a rule for converting each of the following forms of
<Condition> to relational algebra. All conditions may be
assumed to be applied (by a two-argument selection) to a
relation R. You may assume that the subquery is not
correlated with R. Be careful that you do not introduce or
eliminate duplicates in opposition to the formal definition
of SQL.
a) A condition of the form EXISTS (<Query>)
b) A condition of the form a = ANY (<Query>), where a is
an attribute of R.
b) A condition of the form a = ALL (<Query>), where a is
an attribute of R.
Repeat Ex 16.3.3, but allow the subquery to be correlated with R. For simplicity, you may assume that the subquery has the simple form of select-from-where expression described in this section, with no further subqueries.