Saving a connection string

[Jefferies, Brian]

Why does this example work...

      $dbh = DBI->connect("DBI:mysql:database=$database:host=$hostname",
$user, $password) 

...but this doesn't...

      $connect_string = qq("DBI:mysql:database=$database:host=$hostname",
$user, $password);
      $dbh = DBI->connect($connect_string) 

ERROR> Can't connect("DBI:mysql:database=xxxx:host=localhost", xxxx, xxxx), 
ERROR> no database driver specified and DBI_DSN env var not set at ./test.pl
line 29

Is there a better method for saving a connection string?

Thanks in advance,
-Brian