To run a query directly on a SQLite file, the sqlite extension is required. This can be installed use the INSTALL SQL command. This only needs to be run once.

INSTALL sqlite;

To load the sqlite extension for usage, use the LOAD SQL command:

LOAD sqlite;

After the SQLite extension is installed, tables can be queried from SQLite using the sqlite_scan function:

-- scan the table "tbl_name" from the SQLite file "test.db"
SELECT * FROM sqlite_scan('test.db', 'tbl_name');

Alternatively, the entire file can be attached using the sqlite_attach command. This creates views over all of the tables in the file that allow you to query the tables using regular SQL syntax.

-- attach the SQLite file "test.db"
CALL sqlite_attach('test.db');
-- the table "tbl_name" can now be queried as if it is a regular table
SELECT * FROM tbl_name;

For more information see the SQLite scanner documentation.