Oracle date "Between" Query

You need to convert those to actual dates instead of strings, try this:

SELECT *
FROM <TABLENAME>
WHERE start_date BETWEEN TO_DATE('2010-01-15','YYYY-MM-DD') AND TO_DATE('2010-01-17', 'YYYY-MM-DD');

Edited to deal with format as specified:

SELECT *
FROM <TABLENAME>
WHERE start_date BETWEEN TO_DATE('15-JAN-10','DD-MON-YY') AND TO_DATE('17-JAN-10','DD-MON-YY');

Judging from your output it looks like you have defined START_DATE as a timestamp. If it were a regular date Oracle would be able to handle the implicit conversion. But as it isn't you need to explicitly cast those strings to be dates.

SQL> alter session set nls_date_format = 'dd-mon-yyyy hh24:mi:ss'
  2  /

Session altered.

SQL>
SQL> select * from t23
  2  where start_date between '15-JAN-10' and '17-JAN-10'
  3  /

no rows selected

SQL> select * from t23
  2  where start_date between to_date('15-JAN-10') and to_date('17-JAN-10')
  3  /

WIDGET                          START_DATE
------------------------------  ----------------------
Small Widget                    15-JAN-10 04.25.32.000    

SQL> 

But we still only get one row. This is because START_DATE has a time element. If we don't specify the time component Oracle defaults it to midnight. That is fine for the from side of the BETWEEN but not for the until side:

SQL> select * from t23
  2  where start_date between to_date('15-JAN-10') 
  3                       and to_date('17-JAN-10 23:59:59')
  4  /

WIDGET                          START_DATE
------------------------------  ----------------------
Small Widget                    15-JAN-10 04.25.32.000
Product 1                       17-JAN-10 04.31.32.000

SQL>

edit

If you cannot pass in the time component there are a couple of choices. One is to change the WHERE clause to remove the time element from the criteria:

where trunc(start_date) between to_date('15-JAN-10') 
                            and to_date('17-JAN-10')

This might have an impact on performance, because it disqualifies any b-tree index on START_DATE. You would need to build a function-based index instead.

Alternatively you could add the time element to the date in your code:

where start_date between to_date('15-JAN-10') 
                     and to_date('17-JAN-10') + (86399/86400) 

Because of these problems many people prefer to avoid the use of between by checking for date boundaries like this:

where start_date >= to_date('15-JAN-10') 
and start_date < to_date('18-JAN-10')