mybatis进击四：原始SQL查询

素颜马尾好姑娘i 2023-03-12 12:25 9阅读 0赞

**目录**

一、原始SQL查询

二、缺点

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## 一、原始SQL查询 ##

public static void main(String[] args) throws ClassNotFoundException, SQLException {
            // 四大参数
            // MySQL 8.0 以上版本 - JDBC 驱动名及数据库 URL
            String JDBC_DRIVER = "com.mysql.jdbc.Driver";
            String DB_URL = "jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC";
            String USER = "root";
            String PASS = "123456";
    
            // 数据库对象
            Connection connection;
            Statement statement;
            PreparedStatement preparedStatement;
            ResultSet resultSet;
    
            //查询语句
            String rawSql = "select * from test";
            String preparedSql = "select * from test where id = ?";
            Class.forName(JDBC_DRIVER);
    
            connection = DriverManager.getConnection(DB_URL, USER, PASS);
            statement = connection.createStatement();
            resultSet = statement.executeQuery(rawSql);
            print(resultSet);
    
            preparedStatement = connection.prepareStatement(preparedSql);
            preparedStatement.setInt(1, 1);
            resultSet = preparedStatement.executeQuery();
            print(resultSet);
        }
    
        private static void print(ResultSet resultSet) throws SQLException {
            while (resultSet.next()) {
                Integer id = resultSet.getInt("id");
                Integer testTiny1 = resultSet.getInt("test_tiny_1");
                Integer testTiny2 = resultSet.getInt("test_tiny_2");
                String testSnapshot = resultSet.getString("test_snapshot");
                System.out.println("id=" + id  + "\ttestTiny1=" + testTiny1 + "\t testTiny2=" + testTiny2 + "\ttestSnapshot=" + testSnapshot);
            }
        }

## 二、缺点 ##

1、数据库连接每次都要配置 （可以写成静态的）

2、每次都建立connection （可以写成线程池）

3、sql语句需要自己拼接 （这个如何改进）

4、解析ResultSet 麻烦