A lot of other databases support IF [ NOT ] EXISTS clauses with all DDL statements, which can come in very handy when doing migrations and you're not sure if parts of a migration already ran, previously. For example:
CREATE TABLE IF NOT EXISTS t(a number);
ALTER TABLE t ADD COLUMN IF NOT EXISTS b number;
DROP TABLE IF EXISTS t;
I know this can be done with EXECUTE IMMEDIATE and a PL/SQL exception block
BEGIN
EXECUTE IMMEDIATE 'CREATE TABLE t(a number)';
EXCEPTION
WHEN OTHERS THEN NULL;
END;
/
... but the IF [ NOT ] EXISTS form is much more concise