If you use the ISO/IEC 9075:1989 standard, avoid using these words because they may become ANSI SQL reserved words in the future.
after, alias, async
before, boolean, breadth
call, completion, cycle
data, depth, dictionary
each, elseif, equals
general
ignore
leave, less, limit, loop
modify
new, none
object, oid, old, operation, operators, others
parameters, pendant, preorder, private, protected
recursive, ref, referencing, resignal, return, returns, routine, row
savepoint, search, sensitive, sequence, signal, similar, sqlexception, structure
test, there, type
under
variable, virtual, visible
wait, without