diff --git a/src/main/java/mate/academy/Main.java b/src/main/java/mate/academy/Main.java
index 8d43b505..c2b117ae 100644
--- a/src/main/java/mate/academy/Main.java
+++ b/src/main/java/mate/academy/Main.java
@@ -9,36 +9,33 @@
 
 public class Main {
     private static final Injector INJECTOR = Injector.getInstance("mate.academy");
-    private static final Book BOOK_1 = new Book("OnePiece", new BigDecimal(195));
-    private static final Book BOOK_1_UPDATE = new Book(1L, "OnePice", new BigDecimal(250));
-    private static final Book BOOK_2 = new Book("Naruto", new BigDecimal(235));
-    private static final Book BOOK_3 = new Book("Jujutsu Kaisen", new BigDecimal(243));
 
     public static void main(String[] args) {
         BookDao bookDao = (BookDao) INJECTOR.getInstance(BookDao.class);
 
-        bookDao.create(BOOK_1);
-        bookDao.create(BOOK_2);
-        bookDao.create(BOOK_3);
+        List<Book> books = List.of(
+               new Book("OnePiece", new BigDecimal(195)),
+               new Book("Naruto", new BigDecimal(235)),
+               new Book("Jujutsu Kaisen", new BigDecimal(243))
+        );
 
-        bookDao.update(BOOK_1_UPDATE);
+        books.forEach(bookDao::create);
 
-        List<Book> books = bookDao.findAll();
+        Book book1Update = new Book(1L, "OnePiece", new BigDecimal(250));
+        Book updatedBook = bookDao.update(book1Update);
+        System.out.println("Updated book: " + updatedBook);
+
+        List<Book> allBooks = bookDao.findAll();
         System.out.println("All books:");
-        for (Book book : books) {
-            System.out.println(book);
-        }
+        allBooks.forEach(System.out::println);
 
-        Optional<Book> findById = bookDao.findById(1L);
-        System.out.println("Book found id: " + findById);
+        Optional<Book> bookById = bookDao.findById(1L);
+        System.out.println("Book found by id: " + bookById.orElse(null));
 
         bookDao.deleteById(3L);
 
         List<Book> listAfterDelete = bookDao.findAll();
         System.out.println("List after delete by id:");
-        for (Book book : listAfterDelete) {
-            System.out.println(book);
-        }
-
+        listAfterDelete.forEach(System.out::println);
     }
 }
diff --git a/src/main/java/mate/academy/dao/BookDaoImpl.java b/src/main/java/mate/academy/dao/BookDaoImpl.java
index 20b2d9ec..0403c076 100644
--- a/src/main/java/mate/academy/dao/BookDaoImpl.java
+++ b/src/main/java/mate/academy/dao/BookDaoImpl.java
@@ -7,6 +7,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
+import mate.academy.exception.DataProcessingException;
 import mate.academy.lib.Dao;
 import mate.academy.model.Book;
 import mate.academy.util.ConnectionUtil;
@@ -17,18 +18,19 @@ public class BookDaoImpl implements BookDao {
     public Book create(Book book) {
         String query = "INSERT INTO books (title, price) VALUES (?, ?)";
         try (Connection connection = ConnectionUtil.getConnection();
-                       PreparedStatement preparedStatement = connection.prepareStatement(query,
+                PreparedStatement preparedStatement = connection.prepareStatement(query,
                         PreparedStatement.RETURN_GENERATED_KEYS)) {
             preparedStatement.setString(1, book.getTitle());
             preparedStatement.setBigDecimal(2, book.getPrice());
             preparedStatement.executeUpdate();
-            ResultSet resultSet = preparedStatement.getGeneratedKeys();
-            if (resultSet.next()) {
-                book.setId(resultSet.getLong(1));
+            ResultSet generatedKeys = preparedStatement.getGeneratedKeys();
+            if (generatedKeys.next()) {
+                Long id = generatedKeys.getLong(1);
+                book.setId(id);
             }
             return book;
         } catch (SQLException e) {
-            throw new RuntimeException("Failed to create a book", e);
+            throw new DataProcessingException("Failed to create a book", e);
         }
     }
 
@@ -41,13 +43,13 @@ public Optional<Book> findById(Long id) {
             ResultSet resultSet = preparedStatement.executeQuery();
             if (resultSet.next()) {
                 return Optional.of(new Book(
-                        resultSet.getLong("id"),
-                        resultSet.getString("title"),
-                        resultSet.getBigDecimal("price")));
+                       resultSet.getLong("id"),
+                       resultSet.getString("title"),
+                       resultSet.getBigDecimal("price")));
             }
             return Optional.empty();
         } catch (SQLException e) {
-            throw new RuntimeException("Failed to find a book by id: " + id, e);
+            throw new DataProcessingException("Failed to find a book by id: " + id, e);
         }
     }
 
@@ -66,7 +68,7 @@ public List<Book> findAll() {
             }
             return books;
         } catch (SQLException e) {
-            throw new RuntimeException("Failed to find all books", e);
+            throw new DataProcessingException("Failed to find all books", e);
         }
     }
 
@@ -81,7 +83,7 @@ public Book update(Book book) {
             preparedStatement.executeUpdate();
             return book;
         } catch (SQLException e) {
-            throw new RuntimeException("Failed to update a book", e);
+            throw new DataProcessingException("Failed to update a book", e);
         }
     }
 
@@ -93,7 +95,7 @@ public boolean deleteById(Long id) {
             preparedStatement.setLong(1, id);
             return preparedStatement.executeUpdate() > 0;
         } catch (SQLException e) {
-            throw new RuntimeException("Failed to delete a book with id: " + id, e);
+            throw new DataProcessingException("Failed to delete a book with id: " + id, e);
         }
     }
 }
diff --git a/src/main/java/mate/academy/util/ConnectionUtil.java b/src/main/java/mate/academy/util/ConnectionUtil.java
index 0fa9bb1b..52db8f1e 100644
--- a/src/main/java/mate/academy/util/ConnectionUtil.java
+++ b/src/main/java/mate/academy/util/ConnectionUtil.java
@@ -6,8 +6,8 @@
 import java.util.Properties;
 
 public class ConnectionUtil {
-    private static final String DB_URL = "jdbc:mysql:"
-            + "//localhost:3306/mydatabase?serverTimezone=UTC";
+    private static final String DB_URL =
+            "jdbc:mysql://localhost:3306/mydatabase?serverTimezone=UTC";
     private static final Properties DB_PROPERTIES;
 
     static {