diff -r c27eee1259bd -r ed2e7aef2a3e src/main/java/de/uapcore/lightpit/dao/UserDao.java
--- a/src/main/java/de/uapcore/lightpit/dao/UserDao.java	Fri Oct 09 19:06:51 2020 +0200
+++ b/src/main/java/de/uapcore/lightpit/dao/UserDao.java	Fri Oct 09 19:07:05 2020 +0200
@@ -32,8 +32,19 @@
 
 import java.sql.SQLException;
 import java.util.List;
+import java.util.Optional;
 
 public interface UserDao extends GenericDao<User> {
 
     List<User> list() throws SQLException;
+
+    /**
+     * Tries to find a user by their username.
+     * The search is case-insensitive.
+     *
+     * @param username the username
+     * @return the user object or an empty optional if no such user exists
+     * @throws SQLException
+     */
+    Optional<User> findByUsername(String username) throws SQLException;
 }