diff --git a/src/educoder/core/__init__.py b/src/educoder/core/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/educoder/core/permission/__init__.py b/src/educoder/core/permission/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/educoder/core/permission/permission.py b/src/educoder/core/permission/permission.py
new file mode 100644
index 0000000..3cc0510
--- /dev/null
+++ b/src/educoder/core/permission/permission.py
@@ -0,0 +1,8 @@
+from enum import Enum, unique
+
+
+@unique
+class Permission(Enum):
+    NONE = 0
+    USER = 1
+    ADMIN = 2
diff --git a/src/educoder/database/database.py b/src/educoder/database/database.py
index 3318868..ee1aff6 100644
--- a/src/educoder/database/database.py
+++ b/src/educoder/database/database.py
@@ -1,3 +1,39 @@
+from src.educoder.core.permission.permission import Permission
+
+
 class Database(object):
-    def connection(self):
+    def addBook(self, unique_id, isbn, state):
         pass
+
+    def removeBook(self, unique_id):
+        pass
+
+    def addUser(self, user_id, userpass_word, permission: Permission, nick_name):
+        pass
+
+    def modifyUserPermission(self, user_id, permission: Permission):
+        pass
+
+    def removeUser(self, unique_id):
+        pass
+
+    def addBookInformation(self, isbn, author, description, price, made_time, image, category):
+        pass
+
+    def removeBookInformation(self, isbn):
+        pass
+
+    def brownBook(self, unique_id, brownuser):
+        pass
+
+    def stillBook(self, unique_id):
+        pass
+
+    def addCategory(self, category):
+        pass
+
+    def removeCategory(self, category):
+        pass
+
+    def login(self, user_id, password):
+        return True