Oracle commands for MySQL/PostgreSQL users

Oracle tips for MySQL users:

• Simple range: SELECT * FROM (SELECT * FROM foo) WHERE ROWNUM <= 100; -- equivalent of MySQL's LIMIT clause, only for start of table
• Wrong range: SELECT * FROM (SELECT rownum r, f.bar FROM schema.foo f) WHERE r > 100 AND r <= 200; -- Selects a range, but order will be inconsistent, even if you add ORDER BY to inner select
• Right range:

  SELECT * FROM (
      SELECT q.*, ROWNUM r FROM (
          SELECT * FROM schema.foo ORDER BY id
      ) q
  ) WHERE r >= 100 AND r < 200

  (source)
• SELECT last_name FROM employees WHERE last_name LIKE '%d_g\_cat%' ESCAPE '\';
• matches dog_cat, foodig_catbar, etc.
• _ = any single character
• % = any characters
• \_ = literal _ (underscore)
• ESCAPE '\'; -- set the escape character to \ (backslash)
• SELECT ...... WHERE REGEXP_LIKE (instance_name, '^Ste(v|ph)en$');
• ALTER USER foo IDENTIFIED BY "newpassword456!" REPLACE "oldpassword123!"; -- change password (REPLACE is new in 9.2)

(Oracle docs, basic elements, datatypes, conditions)
(source)