jdbc-solution - V1.0 #313
jdbc-solution - V1.0 #313
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| public static Connection getConnection() throws SQLException { | ||
| return DriverManager.getConnection(DB_PATH, PROPERTIES); | ||
| } |
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let's catch exception closer to its origin
| public class BookDaoImpl implements BookDao { | ||
| private List<Book> books = new ArrayList<>(); | ||
| private Long idCounter = 1L; |
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this implementation is wrong
we are learning to use MySQL. Please check common mistakes to see some examples
Or come to QnA to discuss it
src/main/resources/init_db.sql
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| id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, | ||
| title VARCHAR(255), | ||
| price DECIMAL | ||
| ); |
| statement.setString(1, book.getTitle()); | ||
| statement.setBigDecimal(2, book.getPrice()); | ||
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| int affectedRows = statement.executeUpdate(); | ||
| if (affectedRows < 1) { |
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magic numbers, check other methods as well
| if (affectedRows < 1) { | ||
| throw new DataProcessingException( | ||
| "Expected to insert at least one row, but inserted 0 rows for book: " | ||
| + book); | ||
| } |
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code duplication in the update method, extract it to a method
| } | ||
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| private Book mapResultToBook(ResultSet resultSet) throws SQLException { | ||
| Long id = resultSet.getLong("id"); |
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as it was mentioned in the common mistakes
| Long id = resultSet.getLong("id"); | |
| Long id = resultSet.getObject("id", Long.class); |
| Long id = resultSet.getLong("id"); | ||
| String title = resultSet.getString("title"); | ||
| BigDecimal price = resultSet.getObject("price", BigDecimal.class); |
src/main/resources/init_db.sql
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| @@ -0,0 +1,6 @@ | |||
| USE jdbc; | |||
| CREATE TABLE books ( | |||
| id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, | |||
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Primary key already contains not null constraint in it
| id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, | |
| id INT AUTO_INCREMENT PRIMARY KEY, |
src/main/resources/init_db.sql
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| CREATE TABLE books ( | ||
| id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, | ||
| title VARCHAR(255), | ||
| price DECIMAL |
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I'd rather specify the ranges
| price DECIMAL | |
| price DECIMAL(10,2) |
| long columnId = resultSet.getObject(ID, Long.class); | ||
| BigDecimal columnPrice = resultSet.getObject(PRICE, BigDecimal.class); | ||
| String columnTitle = resultSet.getString(TITLE); | ||
| book.setTitle(columnTitle); | ||
| book.setPrice(columnPrice); | ||
| book.setId(columnId); |
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move it back to a separate method please =) this logic is duplicated so it should live in a separate method
| book.setTitle(title); | ||
| book.setPrice(price); | ||
| return book; | ||
| private boolean checkChanges(int affectedRows, Book book) { |
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please think about a more meaningful name
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