Ability to open connection without database name about do

[jpr5]

I've wanted this as well, for administrative functionality like testing if databases exist, creating them, etc.

AFAICT, it's not possible with the current URI-oriented design. My workaround was to connect to known-existing DBs ("mysql" for MySQL) and then use that repository.adapter's connection. However that only works with lax permissions.

[postmodern]

It should be possible to implement this using the current URI model. When path is "" or "/", no database should be selected. This constraint is actually implemented in each C-extension.

https://github.com/datamapper/do/blob/master/do_mysql/ext/do_mysql/do_mysql.c#L230-232
https://github.com/datamapper/do/blob/master/do_postgres/ext/do_postgres/do_postgres.c#L397-399

These constraints could be removed from the C-extensions, and moved to dm-core or dm-rails, where you actually need to connect to a specific database.