java – PreparedStatement：如何使用JDBC将数据插入到多个表中

发布时间：2020-12-15 00:01:28 所属栏目：Java 来源：网络整理

导读：有人能告诉我是否第一个stmt.close();以下JDBC代码中是否需要针对两个不同的表执行两个不同的SQL查询？ public class MyService { private Connection connection = null; public void save(Book book) { try { Class.forName("com.mysql.jdbc.Driver"); con

有人能告诉我是否第一个stmt.close();以下JDBC代码中是否需要针对两个不同的表执行两个不同的SQL查询？

public class MyService {
    private Connection connection = null;

    public void save(Book book) {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb","root","password"); 

            PreparedStatement stmt = connection.prepareStatement("INSERT INTO PUBLISHER (CODE,PUBLISHER_NAME) VALUES (?,?)");
            stmt.setString(1,book.getPublisher().getCode());   
            stmt.setString(2,book.getPublisher().getName());           
            stmt.executeUpdate();

            stmt.close(); //1

            stmt = connection.prepareStatement("INSERT INTO BOOK (ISBN,BOOK_NAME,PUBLISHER_CODE) VALUES (?,?,book.getIsbn());  
            stmt.setString(2,book.getName());
            stmt.setString(3,book.getPublisher().getCode());
            stmt.executeUpdate();

            stmt.close(); //2       
        } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } 
        finally { connection.close(); }         
    }
}

解决方法

在我的书中,我总是建议关闭已经打开的资源以避免可能的泄漏.

稍微更现代的方式是使用try-with-resources：

try (Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb","password")) {

    try (PreparedStatement stmt = connection.prepareStatement("INSERT INTO PUBLISHER (CODE,?)")) {
        stmt.setString(1,book.getPublisher().getCode());   
        stmt.setString(2,book.getPublisher().getName());           
        stmt.executeUpdate();
    }
    // stmt is auto closed here,even if SQLException is thrown

    try (PreparedStatement stmt = connection.prepareStatement("INSERT INTO BOOK (ISBN,?)");
        stmt.setString(1,book.getIsbn());  
        stmt.setString(2,book.getName());
        stmt.setString(3,book.getPublisher().getCode());
        stmt.executeUpdate();
    }
    // stmt is auto closed here,even if SQLException is thrown
}
// connection is auto closed here,even if SQLException is thrown

（编辑：李大同）

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