made corrections

.gitignore

@@ -1,4 +1,3 @@
 .idea/*
 *.iml
 target/*
-src/main/resources/db/db.properties

src/main/java/mate/academy/dao/BookDaoImpl.java

@@ -70,11 +70,8 @@ public Optional<Book> findById(Long id) {
             ResultSet resultSet = preparedStatement.executeQuery();
 
             if (resultSet.next()) {
-                Long identify = resultSet.getObject(FIRST_COLUMN_INDEX, Long.class);
-                String title = resultSet.getObject(SECOND_COLUMN_INDEX, String.class);
-                BigDecimal price = resultSet.getObject(THIRD_COLUMN_INDEX, BigDecimal.class);
+                Book book = mapResultSetToBook(resultSet);
 
-                Book book = new Book(identify, title, price);
                 optionalBook = Optional.of(book);
             }
         } catch (SQLException e) {
@@ -89,15 +86,12 @@ public List<Book> findAll() {
         List<Book> bookList = new ArrayList<>();
         try (Connection connection = ConnectionUtil.getConnection();
                 PreparedStatement preparedStatement = connection
-                        .prepareStatement(SQL_OUTPUT_REQUEST)) {
+                           .prepareStatement(SQL_OUTPUT_REQUEST)) {
             ResultSet resultSet = preparedStatement.executeQuery();
 
             while (resultSet.next()) {
-                Long id = resultSet.getObject(FIRST_COLUMN_INDEX, Long.class);
-                String title = resultSet.getObject(SECOND_COLUMN_INDEX, String.class);
-                BigDecimal price = resultSet.getObject(THIRD_COLUMN_INDEX, BigDecimal.class);
+                Book book = mapResultSetToBook(resultSet);
 
-                Book book = new Book(id, title, price);
                 bookList.add(book);
             }
 
@@ -112,7 +106,7 @@ public List<Book> findAll() {
     public Book update(Book book) {
         try (Connection connection = ConnectionUtil.getConnection();
                 PreparedStatement preparedStatement = connection
-                        .prepareStatement(SQL_UPDATE_REQUEST)) {
+                              .prepareStatement(SQL_UPDATE_REQUEST)) {
             preparedStatement.setString(FIRST_PARAMETER_INDEX, book.getTitle());
             preparedStatement.setBigDecimal(SECOND_PARAMETER_INDEX, book.getPrice());
             preparedStatement.setLong(THIRD_PARAMETER_INDEX, book.getId());
@@ -134,7 +128,7 @@ public boolean deleteById(Long id) {
         int affectedRows = 0;
         try (Connection connection = ConnectionUtil.getConnection();
                 PreparedStatement preparedStatement = connection
-                        .prepareStatement(SQL_DELETE_REQUEST)) {
+                           .prepareStatement(SQL_DELETE_REQUEST)) {
             preparedStatement.setLong(FIRST_PARAMETER_INDEX, id);
             affectedRows = preparedStatement.executeUpdate();
         } catch (SQLException e) {
@@ -143,4 +137,16 @@ public boolean deleteById(Long id) {
         }
         return affectedRows > 0;
     }
+
+    private Book mapResultSetToBook(ResultSet resultSet) {
+        try {
+            Long id = resultSet.getObject(FIRST_COLUMN_INDEX, Long.class);
+            String title = resultSet.getObject(SECOND_COLUMN_INDEX, String.class);
+            BigDecimal price = resultSet.getObject(THIRD_COLUMN_INDEX, BigDecimal.class);
+
+            return new Book(id, title, price);
+        } catch (SQLException e) {
+            throw new DataProcessingException("Error mapping ResultSet to Book", e);
+        }
+    }
 }

src/main/java/mate/academy/db/db.properties → src/main/resources/db.properties

@@ -1,3 +1,3 @@
 db.url=jdbc:mysql://localhost:3306/test
 db.user=root
-db.password=QWERTY123
+db.password=QWERTY123

src/main/resources/init_db.sql

@@ -1,5 +1,5 @@
 CREATE TABLE books (
-   id BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT,
+   id BIGINT PRIMARY KEY AUTO_INCREMENT,
    title VARCHAR(255) NOT NULL,
    price DECIMAL(10, 2) NOT NULL,
    UNIQUE (id)