2 use SDBM_File;
      3 use MLDBM qw (SDBM_File);
      4 use Fcntl;
      5
      6 #tie (%h, 'MLDBM', 'dbm_file', O_CREAT|O_RDWR, 0666) || die "c
+ouldnt open tie-file\n";
      7
      8 $h{ "1" } = { "a" => "first" };
      9 $h{ "2" } = { "a" => "second" };
     10 $h{ "3" } = { "a" => "third" };
     11
     12 foreach ( keys %h )
     13 {
     14     $value = ${ $h{ $_ } }{ "a" };
     15     print "key: .$_. value: .$value.\n";
     16 };
     17 
     18 if ( exists $h{ "1" } )
     19 {   
     20     $h{ "1" } = [ "a", "b", "c" ];
     21     
     22     foreach ( @{ $h{ "1" } } )
     23     {   
     24         print "value is: .$_.\n";
     25     };
     26 };
[download]

key: .1. value: .first.
key: .2. value: .second.
key: .3. value: .third.
value is: .a.
value is: .b.
value is: .c.
[download]

key: .1. value: .first.
key: .2. value: .second.
key: .3. value: .third.
SDBM_File doesn't define an EXISTS method at dbm.pl line 18
[download]

You could just use defined() in this case, but exists() does work on most dbm implementations. Instead of SDBM_File, try DB_File, GDBM_File, or NDBM_File.