On Oct 14, 2011, at 7:31 PM, Bill Ward wrote: > On Fri, Oct 14, 2011 at 5:26 PM, ZhangJun <gb2...@gmail.com> wrote: > >> >> in the pod: >> >> #################### >> Class Methods >> connect >> use DBI; >> >> $dsn = "DBI:mysql:$database"; >> $dsn = "DBI:mysql:database=$database;host=$hostname"; >> $dsn = >> "DBI:mysql:database=$database;host=$hostname;port=$port"; >> >> $dbh = DBI->connect($dsn, $user, $password); >> >> A "database" must always be specified. >> >> ################### >> >> why database is needed ? >> the mysqlclient can connect to server without this, and then select >> database. >> >> > You need to connect to a database before issuing any database commands.
Not necessarily. SHOW DATABASES, for example, doesn't need any database selected. In the connect call, the database following the second colon actually is optional. The second colon, I believe, is not. So "DBI:mysql:" is legal. Or "DBI:mysql::hostname" if you want to specify a hostname. > The > mysql client just makes that easier to do interactively. In Perl you could > just create a different object for each database if you need to connect to > more than one. Why is this a problem? > > -- > Check out my LEGO blog at http://www.brickpile.com/ > View my photos at http://flickr.com/photos/billward/ > Follow me at http://twitter.com/williamward
