DBI defines an interface for communication between R and relational database management systems. All classes in this package are virtual and need to be extended by the various R/DBMS implementations (so-called DBI backends).
A DBI backend is an R package which imports the DBI and methods packages. For better or worse, the names of many existing backends start with ‘R’, e.g., RSQLite, RMySQL, RSQLServer; it is up to the backend author to adopt this convention or not.
A backend defines three classes,
which are subclasses of
The backend provides implementation for all methods
of these base classes
that are defined but not implemented by DBI.
All methods defined in DBI are reexported (so that the package can
be used without having to attach DBI),
and have an ellipsis
... in their formals for extensibility.
The backend must support creation of an instance of its DBIDriver
with a constructor function.
By default, its name is the package name without the leading ‘R’
(if it exists), e.g.,
SQLite for the RSQLite package.
However, backend authors may choose a different name.
The constructor must be exported, and
it must be a function
that is callable without arguments.
DBI recommends to define a constructor with an empty argument list.
Formal specification (currently work in progress and incomplete):
vignette("spec", package = "DBI")
RSQLite::SQLite()#> Warning: replacing previous import ‘DBI::.__C__oldClass’ by ‘methods::.__C__oldClass’ when loading ‘RSQLite’#> Warning: replacing previous import ‘DBI::coerce’ by ‘methods::coerce’ when loading ‘RSQLite’#> Warning: replacing previous import ‘DBI::.__C__character’ by ‘methods::.__C__character’ when loading ‘RSQLite’#> <SQLiteDriver>