[Bioperl-l] About uninitiated string problem

[darson]

Hello,
     I parsed an human unigene database into a MySQL database, then I wrote
a perl script to query from
the database and worked well. My goal is to analyze the BLAST report and
grab the ACC for query on
MySQL database. When the BLAST report is blasted by an human gene sequence,
it worked well.
But if there the BLAST report were non-human sequences, the grabbed ACC
won't get any result from MySQL
query.
     When I used the "SELECT" method to work on it, it replied the "Empty
Set". If I used the DBI module
to use the "SELECT" scripts to do so, the responsed string will show the
"Use of uninitialized value in
concatenation (.) or string at ....." when any further processes. I triedthe
"defined" function in Perl but still
no correct responses. So my question is whether there are any method to
judge the responsed string is valid
(exist in SQL table) or non-valid (non-exist in SQL table). Any suggestions
or comments will be highly
appreciated. Thanks!
                 Best regards
                                           Darson 2003/05/07