Determine if an sqlite3 database is read-only

Question

I'd like to open an sqlite3 database, and immediately check that it is not opened read-only. Since I know I'll need to write to it, I want to return an error immediately at start-up, and not have to wait until a later time when the program first tries to do a write.

I see there is a sqlite3 C API function sqlite3_db_readonly(). Is it possible to access this function from the Python API? Or is there some other way to check if a database is read-only from the Python API?

Answer 1

Apart from other possibilities mentioned, you can just try writing to it. For example, if the user_version of the database is 0 (which it will be unless you have changed it), issue pragma user_version=0;. This will have no effect if the database is writable, but will result in an error if the database is read-only.

Answer 2

no and yes.see the source code of the python standard library sqlite3.

rc = sqlite3_open_v2(database, &self->db,
                        SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
                       (uri ? SQLITE_OPEN_URI : 0), NULL);

this means even if you didn't set the uri,it will open in read-only mode when the file in read-only mode.and search in the code.there are no invoke of sqlite3_db_readonly().so you cannot do it by library sqlite3.

but yes,there are other library,for exampleAPSW.the code

`static PyObject*
Connection_readonly(Connection *self, PyObject *name)
{
  int res=-1;
  res=sqlite3_db_readonly(self->db, PyBytes_AS_STRING(utf8name));
}`

then read the DOC,just call Connection.readonly(name)