prepare migration script to add ulid column

dbmigration/migrate_from_2.1_to_3.0.py

@@ -0,0 +1,38 @@
+#!/usr/bin/python
+# -*- coding: UTF-8 -*-
+
+import sqlite3
+import datetime
+from ulid import ULID
+
+# add column ulid
+connection = sqlite3.connect("db.sqlite")
+cursor = connection.cursor()
+script = """
+PRAGMA foreign_keys = OFF;
+BEGIN TRANSACTION;
+ALTER TABLE comment ADD ulid INTEGER;
+COMMIT;
+PRAGMA foreign_keys = ON;
+"""
+cursor.executescript(script)
+connection.close()
+
+# fill in ulid column
+connection = sqlite3.connect("db.sqlite")
+cursor = connection.cursor()
+updates = []
+for row in cursor.execute('SELECT * FROM comment'):
+    row_id = row[0]
+    string_created = row[2]
+    date_created = datetime.datetime.strptime(string_created, "%Y-%m-%d %H:%M:%S")
+    ulid = ULID.from_datetime(date_created)
+    update = "UPDATE comment SET ulid = " + str(int(ulid)) + " WHERE id = " + str(row_id)
+    print(update)
+    updates.append(update)
+
+for update in updates:
+    pass
+    connection.execute(update)
+connection.commit()
+connection.close()