Ocamlnet 4 Reference Manual : Netcgi_dbi.DBI_DRIVER

`sig
type connection
val connect :
?host:string ->
?port:string ->
?user:string ->
?password:string -> string -> Netcgi_dbi.DBI_DRIVER.connection
val close : Netcgi_dbi.DBI_DRIVER.connection -> unit
val closed : Netcgi_dbi.DBI_DRIVER.connection -> bool
val commit : Netcgi_dbi.DBI_DRIVER.connection -> unit
val ping : Netcgi_dbi.DBI_DRIVER.connection -> bool
val rollback : Netcgi_dbi.DBI_DRIVER.connection -> unit
end`