"""A single connection to the database."""
 
     def __init__(self, db_file: DatabaseFile) -> None:
-        self.conn = sql_connect(db_file.path)
-
-    def commit(self) -> None:
-        """Commit SQL transaction."""
-        self.conn.commit()
+        self._conn = sql_connect(db_file.path)
+        self.commit = self._conn.commit
+        self.close = self._conn.close
 
     def exec(self,
              code: str,
             if build_q_marks:
                 q_marks = ('?' if len(inputs) == 1
                            else '(' + ','.join(['?'] * len(inputs)) + ')')
-                return self.conn.execute(f'{code} {q_marks}', inputs)
-            return self.conn.execute(code, inputs)
-        return self.conn.execute(code)
-
-    def close(self) -> None:
-        """Close DB connection."""
-        self.conn.close()
+                return self._conn.execute(f'{code} {q_marks}', inputs)
+            return self._conn.execute(code, inputs)
+        return self._conn.execute(code)
 
     def rewrite_relations(self, table_name: str, key: str, target: int | str,
                           rows: list[list[Any]], key_index: int = 0) -> None: