Invoking MySQL without a username or a password defaults to the current login and no password:
perl -MDBI -we'my $dbh=DBI->connect("dbi:mysql:","","")'
DBI connect('','',...) failed: Access denied for user 'ben'@'localhost
+' (using password: NO) at -e line 1
...and there doesn't seem to be any way to force it to accept a blank username, either:
mysql --user="" --password=""
ERROR 1045 (28000): Access denied for user 'ben'@'localhost' (using pa
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