diff -r 1574965c7dc7 -r 57cfb94ab99f src/main/java/de/uapcore/lightpit/dao/AbstractDao.java
--- a/src/main/java/de/uapcore/lightpit/dao/AbstractDao.java	Wed May 13 21:46:26 2020 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,96 +0,0 @@
-/*
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
- *
- * Copyright 2018 Mike Becker. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- *   1. Redistributions of source code must retain the above copyright
- *      notice, this list of conditions and the following disclaimer.
- *
- *   2. Redistributions in binary form must reproduce the above copyright
- *      notice, this list of conditions and the following disclaimer in the
- *      documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- */
-package de.uapcore.lightpit.dao;
-
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
-import java.sql.SQLException;
-import java.sql.Types;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Optional;
-import java.util.function.Function;
-
-public abstract class AbstractDao<T> implements GenericDao<T> {
-
-    private final PreparedStatement listQuery;
-
-    protected AbstractDao(PreparedStatement listQuery) {
-        this.listQuery = listQuery;
-    }
-
-    public final T mapColumns(ResultSet result) throws SQLException {
-        return mapColumns(result, "");
-    }
-
-    public abstract T mapColumns(ResultSet result, String qualifier) throws SQLException;
-
-    /**
-     * Qualifies a column label if an qualifier is specified.
-     *
-     * @param qualifier an optional qualifier
-     * @param label     the column label
-     * @return the label, qualified if necessary
-     */
-    protected final String qual(String qualifier, String label) {
-        if (qualifier == null || qualifier.isBlank()) {
-            return label;
-        } else {
-            return qualifier + "." + label;
-        }
-    }
-
-    protected final void setStringOrNull(PreparedStatement stmt, int index, String str) throws SQLException {
-        if (str == null || str.isBlank()) {
-            stmt.setNull(index, Types.VARCHAR);
-        } else {
-            stmt.setString(index, str);
-        }
-    }
-
-    protected final <T> void setForeignKeyOrNull(PreparedStatement stmt, int index, T instance, Function<? super T, Integer> keyGetter) throws SQLException {
-        Integer key = Optional.ofNullable(instance).map(keyGetter).orElse(null);
-        if (key == null) {
-            stmt.setNull(index, Types.INTEGER);
-        } else {
-            stmt.setInt(index, key);
-        }
-    }
-
-    @Override
-    public List<T> list() throws SQLException {
-        List<T> list = new ArrayList<>();
-        try (ResultSet result = listQuery.executeQuery()) {
-            while (result.next()) {
-                list.add(mapColumns(result));
-            }
-        }
-        return list;
-    }
-}