通过JDBC连接数据库进行增删改查

通过JDBC连接数据库进行增删改查

DBUtil类——用于存放连接以及管理的方法

public class DBUtil {
    public static Connection getConnection() throws ClassNotFoundException, SQLException {
        Class.forName("com.mysql.jdbc.Driver");

        Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/wzbc", "root", "123456");
        return connection;
    }

    public static void closeAll(ResultSet resultSet, Statement statement, Connection connection) throws SQLException {
        if (resultSet != null) {
            resultSet.close();
        }
        if (statement != null) {
            statement.close();
        }
        if (connection != null) {
            connection.close();
        }
    }
}

Insert类

public class Insert {
    public static void main(String[] args) {
        try {
            Connection connection = DBUtil.getConnection();
            String sql = "INSERT INTO `tb_user` VALUES (null, 'user2', 'user2')";
            PreparedStatement statement = connection.prepareStatement(sql);

            statement.executeUpdate();
            System.out.println("Successful execution");

            DBUtil.closeAll(null, statement, connection);
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

Delete类

public class Delete {
    public static void main(String[] args) {
        try {
            Connection connection = DBUtil.getConnection();

            String sql = "delete from tb_user where username = 'user2'";

            PreparedStatement statement = connection.prepareStatement(sql);

            statement.executeUpdate();
            System.out.println("Successful execution");

            DBUtil.closeAll(null, statement, connection);
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

Update类

public class Update {
    public static void main(String[] args) {
        try {
            Connection connection = DBUtil.getConnection();

            String sql = "update tb_user set username = REPLACE(username, 'user2', 'user3') where username = 'user2'";

            PreparedStatement statement = connection.prepareStatement(sql);

            statement.executeUpdate();
            System.out.println("Successful execution");
            DBUtil.closeAll(null, statement, connection);
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

Find类

public class Find {
    public static void main(String[] args) {
        try {
            Connection connection = DBUtil.getConnection();

            String sql = "select * from tb_user";

            PreparedStatement statement = connection.prepareStatement(sql);

            ResultSet resultSet = statement.executeQuery();

            while (resultSet.next()) {
                System.out.println(resultSet.getInt(1));
                System.out.println(resultSet.getString(2));
                System.out.println(resultSet.getString(3));
            }

            System.out.println("Successful execution");

            DBUtil.closeAll(resultSet, statement, connection);
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}