A compound expression specifies a combination of other expressions.
You can use any built-in function as an expression ("Function Expressions"). However, in a compound expression, some combinations of functions are inappropriate and are rejected. For example, the
LENGTH function is inappropriate within an aggregate function.
PRIOR operator is used in
BY clauses of hierarchical queries.
Some valid compound expressions are:
('CLARK' || 'SMITH') LENGTH('MOOSE') * 57 SQRT(144) + 72 my_fun(TO_CHAR(sysdate,'DD-MMM-YY'))