Interesting SQL Query Requirement For &<SELECT&> Menu

Hi All

Wondered if you could help me with the below query.

I have 1 simple table called STOCKCATS that consists of 2 fields.

These fields are called CATID and LEVEL.

The contents of this table are as follows:

CATID LEVEL
cat01 <nothing>
cat02 <nothing>
cat03 cat01
cat04 <nothing>
cat05 cat01
cat06 cat02
cat07 cat04
etc.. etc...

The way this table works is that I have an ASP page that allows the user to
create a stock category at 2 levels, category level and sub-category level.

When I file the entered data into the table, if the user has chosen to
create a category level stock category then the LEVEL field is left blank
and if they chose to create a sub-category level category then I post the
relevant category level stock category code in the LEVEL field. For
example, in the above list cat01 is a category level stock category and
cat05 is a sub-category as it is a sub-category of cat01.

My query is that I want to populate a simple HTML <SELECT> menu (using ASP),
but instead of it being a straightforward 'select catid from stockcats order
by catid', I want to group this list into some kind of order, eg:

instead of:

cat01 <nothing> << I need to bring back this 2nd column so that I can
do a simple IF THEN in asp to indent sub-cats
cat02 <nothing>
cat03 cat01
cat04 <nothing>
cat05 cat01
cat06 cat02
cat07 cat04

I would like

cat01 <nothing> << ditto
cat03 cat01
cat05 cat01
cat02 <nothing>
cat06 cat02
cat04 <nothing>
cat07 cat04

Do you know if this is possible in pure SQL (I must confess that I'm using
MySQL, but I would have thought the SQL syntax would be the same if it is
possible) or a combo of ASP & SQL?

Thanks

Robbie