diff --git a/database.py b/database.py
index f8f4542..6c74564 100644
--- a/database.py
+++ b/database.py
@@ -1,28 +1,25 @@
 import sqlite3
-"""
-Classes:
-Database - implement intercaction with the database.
-"""
 
-class Database():
-    """Implement intercaction with the database."""
+from exceptions import DisplayableException
+
+
+class Database:
+    """Implement interaction with the database."""
 
     def __init__(self, path: str) -> None:
         """Create a database file if not exists."""
-        self.conn = sqlite3.connect(path)
+        # TODO: think about removing check_same_thread=False
+        self.conn = sqlite3.connect(path, check_same_thread=False)
         self.cur = self.conn.cursor()
-        self.cur.execute('CREATE TABLE IF NOT EXISTS users (id INTEGER, telegram_id NUMERIC NOT NULL UNIQUE, PRIMARY KEY(id))')
-        self.cur.execute('CREATE TABLE IF NOT EXISTS feeds (id INTEGER, url TEXT NOT NULL UNIQUE, PRIMARY KEY(id))')
-        self.cur.execute('CREATE TABLE IF NOT EXISTS subscriptions (user_id INTEGER, feed_id INTEGER, UNIQUE (user_id, feed_id), FOREIGN KEY(user_id) REFERENCES users(id), FOREIGN KEY(feed_id) REFERENCES feeds(id))')
-        self.cur.execute('CREATE TABLE IF NOT EXISTS feeds_last_items (feed_id INTEGER, url TEXT NOT NULL UNIQUE, title TEXT, description TEXT, date NUMERIC, FOREIGN KEY(feed_id) REFERENCES feeds(id))')
+        self.__init_schema()
 
-    def add_user(self, telegram_id: str) -> int:
+    def add_user(self, telegram_id: int) -> int:
         """Add a user's telegram id to the database and return its database id."""
         self.cur.execute('INSERT INTO users (telegram_id) VALUES (?)', [telegram_id])
         self.conn.commit()
         return self.cur.lastrowid
 
-    def find_user(self, telegram_id: str) -> int | None:
+    def find_user(self, telegram_id: int) -> int | None:
         """Get a user's telegram id and return its database id."""
         self.cur.execute('SELECT id FROM users WHERE telegram_id = ?', [telegram_id])
         row = self.cur.fetchone()
@@ -36,21 +33,70 @@ class Database():
         self.conn.commit()
         return self.cur.lastrowid
 
+    def find_feed_by_url(self, url: str) -> int | None:
+        """Find feed ID by url."""
+        self.cur.execute('SELECT id FROM feeds WHERE url = ?', [url])
+        row = self.cur.fetchone()
+        if row is None:
+            return None
+        return row[0]
+
+    def subscribe_user_by_url(self, user_id: int, url: str) -> None:
+        """Subscribe user to the feed creating it if does not exist yet."""
+        feed_id = self.find_feed_by_url(url)
+        if feed_id is None:
+            feed_id = self.add_feed(url)
+
+        if self.is_user_subscribed(user_id, feed_id):
+            raise DisplayableException('Already subscribed')
+
+        self.subscribe_user(user_id, feed_id)
+
     def subscribe_user(self, user_id: int, feed_id: int) -> None:
         """Subscribe a user to the feed."""
         self.cur.execute('INSERT INTO subscriptions (user_id, feed_id) VALUES (?, ?)', [user_id, feed_id])
         self.conn.commit()
 
+    def unsubscribe_user_by_url(self, user_id: int, url: str) -> None:
+        feed_id = self.find_feed_by_url(url)
+        if feed_id is None:
+            raise DisplayableException('Feed does not exist')
+
+        if not self.is_user_subscribed(user_id, feed_id):
+            raise DisplayableException('Not subscribed')
+
+        self.unsubscribe_user(user_id, feed_id)
+
+        if self.get_feed_subscribers_count(feed_id) == 0:
+            # Feed is not used anymore. Removing.
+            self.delete_feed(feed_id)
+
     def unsubscribe_user(self, user_id: int, feed_id: int) -> None:
         """Unsubscribe a user from the feed."""
         self.cur.execute('DELETE FROM subscriptions WHERE feed_id = ? AND user_id = ?', [feed_id, user_id])
         self.conn.commit()
 
+    def is_user_subscribed(self, user_id: int, feed_id: int) -> bool:
+        """Check if user subscribed to specific feed."""
+        self.cur.execute('SELECT 1 FROM subscriptions WHERE user_id = ? AND feed_id = ?', [user_id, feed_id])
+        row = self.cur.fetchone()
+        if row is None:
+            return False
+        return True
+
     def delete_feed(self, feed_id: int) -> None:
         """Delete a feed."""
         self.cur.execute('DELETE FROM feeds WHERE id = ?', [feed_id])
         self.conn.commit()
 
+    def get_feed_subscribers_count(self, feed_id: int) -> int:
+        """Count feed subscribers."""
+        self.cur.execute('SELECT COUNT(user_id) FROM subscriptions WHERE feed_id = ?', [feed_id])
+        row = self.cur.fetchone()
+        if row is None:
+            return 0
+        return int(row[0])
+
     def find_feeds(self) -> list:
         """Get a list of feeds."""
         self.cur.execute('SELECT * FROM feeds')
@@ -58,7 +104,8 @@ class Database():
 
     def find_user_feeds(self, user_id: int) -> list:
         """Return a list of feeds the user is subscribed to."""
-        self.cur.execute('SELECT * FROM feeds WHERE id IN (SELECT feed_id FROM subscriptions WHERE user_id = ?)', [user_id])
+        self.cur.execute('SELECT * FROM feeds WHERE id IN (SELECT feed_id FROM subscriptions WHERE user_id = ?)',
+                         [user_id])
         return self.cur.fetchall()
 
     def find_feed_items(self, feed_id: int) -> list:
@@ -72,5 +119,32 @@ class Database():
             new_items[i] = (feed_id,) + new_items[i]
 
         self.cur.execute('DELETE FROM feeds_last_items WHERE feed_id = ?', [feed_id])
-        self.cur.executemany('INSERT INTO feeds_last_items (feed_id, url, title, description, date) VALUES (?, ?, ?, ?, ?)', new_items)
+        self.cur.executemany(
+            'INSERT INTO feeds_last_items (feed_id, url, title, description, date) VALUES (?, ?, ?, ?, ?)', new_items)
         self.conn.commit()
+
+    def __init_schema(self):
+        # TODO: Move to migrations
+        self.cur.execute(
+            'CREATE TABLE IF NOT EXISTS users (id INTEGER, telegram_id INTEGER NOT NULL UNIQUE, PRIMARY KEY(id))'
+        )
+        self.cur.execute('CREATE TABLE IF NOT EXISTS feeds (id INTEGER, url TEXT NOT NULL UNIQUE, PRIMARY KEY(id))')
+        self.cur.execute(
+            'CREATE TABLE IF NOT EXISTS subscriptions ('
+            '   user_id INTEGER,'
+            '   feed_id INTEGER,'
+            '   UNIQUE (user_id, feed_id),'
+            '   FOREIGN KEY(user_id) REFERENCES users(id),'
+            '   FOREIGN KEY(feed_id) REFERENCES feeds(id)'
+            ')'
+        )
+        self.cur.execute(
+            'CREATE TABLE IF NOT EXISTS feeds_last_items ('
+            '   feed_id INTEGER,'
+            '   url TEXT NOT NULL UNIQUE,'
+            '   title TEXT,'
+            '   description TEXT,'
+            '   date NUMERIC,'
+            '   FOREIGN KEY(feed_id) REFERENCES feeds(id)'
+            ')'
+        )
diff --git a/exceptions.py b/exceptions.py
new file mode 100644
index 0000000..5072879
--- /dev/null
+++ b/exceptions.py
@@ -0,0 +1,3 @@
+class DisplayableException(Exception):
+    """Exception which could be safely displayed to the end-user."""
+    pass