text: SET SERVEROUTPUT ON;
  SET AUTOPRINT ON;
  
  /*
      bind variables
      - created in the host environment
      - scope is whole worksheet
  */
  
  VARIABLE var_text VARCHAR2(30);
  -- cannot create with type NUMBER(5,2)
  VARIABLE var_number NUMBER;
  -- cannot create this type of bind variable
  -- VARIABLE var_date DATE; 
  
  DECLARE
      v_text VARCHAR2(30);
  BEGIN
      :var_text := 'Hello Kitty';
      :var_number := 20;
      v_text := :var_text;
      dbms_output.put_line(v_text);
      dbms_output.put_line(:var_text);
  END;
  
  PRINT var_text;
  
  
  /* define and instantiate a variable*/
  VARIABLE var_sql NUMBER;
  BEGIN
      :var_sql := 100;
  END;
  
  /* use the variable in statements */
  SELECT * FROM employees WHERE employee_id = :var_sql;