text: -- UPPER and LOWER functions
  SELECT UPPER(first_name), LOWER(first_name) FROM employees WHERE employee_id = 127;
  
  
  -- Concatenation
  SELECT first_name || last_name fullname FROM employees WHERE employee_id = 127;
  
  -- Trim functions
  SELECT '      ' || first_name without_trim,
         ltrim( '      ' || first_name) with_trim
   FROM employees
  WHERE employee_id = 127;
  
  
  -- LTRIM function
  SELECT ltrim( first_name, 'J') FROM employees WHERE employee_id = 127;
  
  
  -- LPAD function
  SELECT LPAD(first_name, 10, 'x') lpad_ex, RPAD(first_name, 10, 'x') rpad_ex
    FROM employees
   WHERE employee_id = 127;
  
  
  -- Sub string function
  SELECT SUBSTR(first_name, 2, 3) FROM employees WHERE employee_id = 127;
  
  
  -- Aggregate functions
  SELECT COUNT(*), MIN(salary), MAX(salary), AVG(salary) FROM employees;
  
  
  -- ADD_MONTHS function
  SELECT hire_date, ADD_MONTHS(hire_date, 2) FROM employees WHERE employee_id = 127;
  
  -- Conversion functions
  SELECT  TO_NUMBER('11') tonum,
          TO_CHAR('test') tochar,
          TO_DATE('01-01-2012', 'dd-mm-yyyy') todate
    FROM dual;
  
  