Update sql-type methods and reg-ex constraint for SQLite.

stix2/datastore/relational_db/database_backends/sqlite_backend.py

@@ -39,6 +39,18 @@ def determine_sql_type_for_hex_property():  # noqa: F811
         # return LargeBinary
         return SQLiteBackend.determine_sql_type_for_string_property()
 
+    @staticmethod
+    def determine_sql_type_for_reference_property():  # noqa: F811
+        return Text
+
+    @staticmethod
+    def determine_sql_type_for_string_property():  # noqa: F811
+        return Text
+
+    @staticmethod
+    def determine_sql_type_for_key_as_id():  # noqa: F811
+        return Text
+
     @staticmethod
     def determine_sql_type_for_timestamp_property():  # noqa: F811
         return TIMESTAMP(timezone=True)
@@ -49,3 +61,7 @@ def determine_sql_type_for_timestamp_property():  # noqa: F811
     @staticmethod
     def array_allowed():
         return False
+
+    @staticmethod
+    def create_regex_constraint_expression(column_name, pattern):
+        return f"{column_name} ~ {pattern}"