diff --git a/db/SQLiteClient.py b/db/SQLiteClient.py
index 390c94d..9c7d21b 100644
--- a/db/SQLiteClient.py
+++ b/db/SQLiteClient.py
@@ -45,8 +45,7 @@ def get_user_by_email(email: str):
 def update_user(id: int, name: str, email: str, password: str = None):
     now = datetime.now().isoformat()
     if password:
-        query = (f"UPDATE users SET name = '{name}', email = '{email}', password = '{password}', updated_at = '{now}' "
-                 f"WHERE id = {id};")
+        query = f"UPDATE users SET name = '{name}', email = '{email}', password = '{password}', updated_at = '{now}' WHERE id = {id};"
     else:
         query = f"UPDATE users SET name = '{name}', email = '{email}', updated_at = '{now}' WHERE id = {id};"
     conn = con3()
@@ -58,10 +57,12 @@ def update_user(id: int, name: str, email: str, password: str = None):
 
 
 def delete_user(id: int):
-    query = f"DELETE FROM users WHERE id = {id};"
+    query = f"DELETE FROM habit_lists WHERE (SELECT list_id FROM habit_users WHERE user_id = {id}) = id;"
+    query2 = f"DELETE FROM users WHERE id = {id};"
     conn = con3()
     cursor = conn.cursor()
     cursor.execute(query)
+    cursor.execute(query2)
     conn.commit()
     conn.close()
     return cursor.lastrowid
@@ -70,8 +71,8 @@ def delete_user(id: int):
 ### Habit.py ###
 def create_habit(list_id: int, name: str, times: int, unit: int, slot: int, note: str | None=None):
     now = datetime.now().isoformat()
-    query = (f"INSERT INTO habits (list_id, name, note, times, unit, slot, created_at, updated_at) "
-             f"VALUES ('{list_id}', '{name}', '{note}', '{times}', '{unit}', '{slot}', '{now}', '{now}');")
+    query = (f"INSERT INTO habits (list_id, name, note, times, unit, slot, created_at, updated_at) VALUES ('{list_id}', "
+             f"'{name}', '{note}', '{times}', '{unit}', '{slot}', '{now}', '{now}');")
     conn = con3()
     cursor = conn.cursor()
     cursor.execute(query)
@@ -167,8 +168,7 @@ def update_slot(id: int, slot: int):
 
 def update_habit(id: int, name: str, note: str, times: int, unit: int):
     now = datetime.now().isoformat()
-    query = (f"UPDATE habits SET name = {name}, note = {note}, times = {times}, unit = {unit}, updated_at = '{now}' "
-             f"WHERE id = {id};")
+    query = f"UPDATE habits SET name = {name}, note = {note}, times = {times}, unit = {unit}, updated_at = '{now}' WHERE id = {id};"
     conn = con3()
     cursor = conn.cursor()
     cursor.execute(query)
@@ -178,12 +178,10 @@ def update_habit(id: int, name: str, note: str, times: int, unit: int):
 
 
 def delete_habit(id: int):
-    query = f"DELETE FROM habit_trackings WHERE id = habit_id;"
-    query2 = f"DELETE FROM habits WHERE id = {id};"
+    query = f"DELETE FROM habits WHERE id = {id};"
     conn = con3()
     cursor = conn.cursor()
     cursor.execute(query)
-    cursor.execute(query2)
     conn.commit()
     conn.close()
 
@@ -266,37 +264,6 @@ def get_habitLists(user_id: int):
     return habit_lists
 
 
-def get_users(list_id: int):
-    query = (f"SELECT users.* FROM users JOIN habit_users ON users.id = habit_users.user_id WHERE "
-             f"habit_users.list_id = {list_id};")
-    conn = con3()
-    cursor = conn.cursor()
-    cursor.execute(query)
-    users = cursor.fetchall()
-    conn.close()
-    return users
-
-
-def add_user(list_id: int, user_id: int):
-    now = datetime.now().isoformat()
-    query = (f"INSERT INTO habit_users (user_id, list_id, created_at, updated_at)"
-              f" VALUES ('{user_id}', '{list_id}', '{now}', '{now}');")
-    conn = con3()
-    cursor = conn.cursor()
-    cursor.execute(query)
-    conn.commit()
-    conn.close()
-
-
-def remove_user(list_id: int, user_id: int):
-    query = f"DELETE FROM habit_lists WHERE user_id = {user_id} AND list_id = {list_id};"
-    conn = con3()
-    cursor = conn.cursor()
-    cursor.execute(query)
-    conn.commit()
-    conn.close()
-
-
 def update_habitList(id: int, name: str, description: str):
     now = datetime.now().isoformat()
     query = f"UPDATE habit_lists SET name = {name}, description = {description}, updated_at = '{now}' WHERE id = {id};"
@@ -317,6 +284,16 @@ def delete_habitList(id: int):
     conn.close()
 
 
+def get_users(list_id: int):
+    query = f"SELECT users.* FROM users JOIN habit_users ON users.id = habit_users.user_id WHERE habit_users.list_id = {list_id};"
+    conn = con3()
+    cursor = conn.cursor()
+    cursor.execute(query)
+    users = cursor.fetchall()
+    conn.close()
+    return users
+
+
 if __name__ == "__main__":
     habits = get_habits(1)
     for habit in habits:
diff --git a/models/Habit.py b/models/Habit.py
index 35faf65..9c26954 100644
--- a/models/Habit.py
+++ b/models/Habit.py
@@ -3,11 +3,11 @@ from dataclasses import dataclass
 from datetime import datetime
 
 from models.HabitTrackings import HabitTrackings
-from db.SQLiteClient import (create_habit, get_habit, update_habit, delete_habit, get_next_slot, get_slots, update_slot,
-                             get_habitTrackings_by_habit_id, get_habitList)
+from db.SQLiteClient import update_slot, create_habit, get_habit, delete_habit, get_next_slot, \
+    get_habitTrackings_by_habit_id, get_slots, update_habit, get_habitList
 
 
-# Unit wird als Integer wie folgt gemessen:
+# Unit wird als Integers wie folgt gemessen:
 # 0: Tag
 # 1: Woche (Default)
 # 2: Monat
@@ -36,7 +36,9 @@ class Habit:
     @staticmethod
     def get(id: int):
         habit = get_habit(id)
-        return Habit(habit[0], habit[1], habit[2], habit[3], habit[4], habit[5], habit[6]) if habit else None
+        habit = Habit(habit[0], habit[1], habit[2], habit[3], habit[4], habit[5], habit[6]) if habit else None
+
+        return habit
 
     def update(self, name: str=None, note: str=None, times: int=None, unit: int=None):
         update_habit(self.id, name, note, times, unit)
@@ -67,17 +69,13 @@ class Habit:
             update_slot(slot[0], slot[1] - 1)
         delete_habit(self.id)
 
-    def get_habitTrackings(self) -> list:
+    def get_habitTrackings(self) -> list[HabitTrackings]:
         trackings = []
         for rawTracking in get_habitTrackings_by_habit_id(self.id):
-            trackings.append(HabitTrackings(rawTracking[0], rawTracking[1]))
+            trackings.append(HabitTrackings(rawTracking[0], rawTracking[1],
+                                            datetime.strptime(rawTracking[2], "%Y-%m-%dT%H:%M:%S.%f")))
         return trackings
 
-    def habit_list(self):
-        from models.HabitList import HabitList
-        raw_habitLists = get_habitList(self.list_id)
-        return HabitList(raw_habitLists[0], raw_habitLists[1], raw_habitLists[2]) if raw_habitLists else None
-
     def fill_statistics(self):
         count = 0
         self.checked = False
@@ -106,3 +104,11 @@ class Habit:
 
     def to_json(self):
         return json.dumps(self, default=lambda o: o.__dict__, sort_keys=True, indent=4)
+
+    def habit_list(self):
+        from models.HabitList import HabitList
+        raw_habitLists = get_habitList(self.list_id)
+        return HabitList(raw_habitLists[0], raw_habitLists[1], raw_habitLists[2],
+                         datetime.strptime(raw_habitLists[3], "%Y-%m-%dT%H:%M:%S.%f"),
+                         datetime.strptime(raw_habitLists[4], "%Y-%m-%dT%H:%M:%S.%f")) \
+        if raw_habitLists else None
diff --git a/models/HabitList.py b/models/HabitList.py
index 64fa292..d59e265 100644
--- a/models/HabitList.py
+++ b/models/HabitList.py
@@ -1,10 +1,9 @@
 from dataclasses import dataclass
-from datetime import datetime
+from datetime import date, datetime
 
+from db.SQLiteClient import delete_habitList, create_habitList, get_habitList, get_habits, get_users
 from models.Habit import Habit
 from models.User import User
-from db.SQLiteClient import (delete_habitList, create_habitList, get_habitList, get_habits,
-                             get_users, add_user, remove_user)
 
 
 @dataclass
@@ -12,19 +11,24 @@ class HabitList:
     id: int
     name: str
     description: str
+    created_at: date
+    updated_at: date
     habits: list = None
 
     @staticmethod
     def create(user_id: int, name: str, description: str):
         id = create_habitList(user_id, name, description)
-        return HabitList(id, name, description)
+        return HabitList(id, name, description, datetime.now(), datetime.now())
 
     @staticmethod
     def get(id: int):
         habitList = get_habitList(id)
         return HabitList(habitList[0], habitList[1], habitList[2], datetime.strptime(habitList[3], "%Y-%m-%dT%H:%M:%S.%f"), datetime.strptime(habitList[4], "%Y-%m-%dT%H:%M:%S.%f")) if habitList else None
 
-    def get_habits(self) -> list:
+    def delete(self):
+        delete_habitList(self.id)
+
+    def get_habits(self):
         raw_habits = get_habits(self.id)
         habits = []
         for habit in raw_habits:
@@ -33,7 +37,7 @@ class HabitList:
 
         return habits
 
-    def get_users(self) -> list:
+    def get_users(self):
         raw_users = get_users(self.id)
         users = []
         for user in raw_users:
@@ -41,14 +45,3 @@ class HabitList:
             users.append(user)
 
         return users
-
-    def add_user(self, email: str):
-        user = User.get_by_email(email)
-        add_user(self.id, user.id)
-
-    # The id of the current user is necessary
-    def delete(self, user_id):
-        if len(get_users) > 1:
-            remove_user(self.id, user_id)
-        else:
-            delete_habitList(self.id)
diff --git a/models/HabitTrackings.py b/models/HabitTrackings.py
index 996aed6..9ad30f1 100644
--- a/models/HabitTrackings.py
+++ b/models/HabitTrackings.py
@@ -1,4 +1,6 @@
 from dataclasses import dataclass
+from datetime import date, datetime
+
 from db.SQLiteClient import create_habitTrackings, get_habitTrackings, delete_habitTrackings
 
 
@@ -6,16 +8,17 @@ from db.SQLiteClient import create_habitTrackings, get_habitTrackings, delete_ha
 class HabitTrackings:
     id: int
     habit_id: int
+    created_at: date
 
     @staticmethod
-    def create(habit_id: int):
+    def create(habit_id: int, times: int):
         id = create_habitTrackings(habit_id)
-        return HabitTrackings(id, habit_id)
+        return HabitTrackings(id, habit_id, datetime.now())
 
     @staticmethod
     def get(id: int):
         habitTrackings = get_habitTrackings(id)
-        return HabitTrackings(habitTrackings[0], habitTrackings[1]) if habitTrackings else None
+        return HabitTrackings(habitTrackings[0], habitTrackings[1], datetime.strptime(habitTrackings[2], "%Y-%m-%dT%H:%M:%S.%f")) if habitTrackings else None
 
     def delete(self):
         delete_habitTrackings(self.id)
diff --git a/models/User.py b/models/User.py
index e058fc3..13f9f72 100644
--- a/models/User.py
+++ b/models/User.py
@@ -1,8 +1,8 @@
 from datetime import datetime
 
 from flask_login import UserMixin
-from db.SQLiteClient import (create_user, get_user, get_user_by_email, update_user, delete_user,
-                             get_habitLists, get_heatmap_value)
+from db.SQLiteClient import create_user, get_user, get_user_by_email, delete_user, update_user, \
+    get_habitLists, get_heatmap_value
 
 
 class User(UserMixin):
@@ -31,12 +31,9 @@ class User(UserMixin):
         update_user(self.id, self.name, self.email, self.password if self.password else None)
 
     def delete(self):
-        habitLists = self.get_habitLists()
-        for habitList in habitLists:
-            habitList.delete(self.id)
         delete_user(self.id)
 
-    def get_habitLists(self) -> list:
+    def get_habitLists(self):
         from models.HabitList import HabitList
 
         raw_habitLists = get_habitLists(self.id)
@@ -47,7 +44,7 @@ class User(UserMixin):
 
         return habitLists
 
-    def get_heatmap(self) -> list:
+    def get_heatmap(self):
         heatmap = []
         for day in range (0, 27):
             value = get_heatmap_value(self.id, day)