4.JDBC

JDBC

JDBC简介

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JDBC快速入门

步骤

public class JDBCDemo {
    public static void main(String[] args) throws Exception {
        //  1.注册驱动
        Class.forName("com.mysql.jdbc.Driver"); //  可以省略
        //  2.获取连接
        String url = "jdbc:mysql://127.0.0.1:3306/db1";
        String username = "root";
        String password = "8589";
        Connection conn = DriverManager.getConnection(url, username, password);
        //  3.定义SQL
        String sql = "UPDATE account set money = 2000 WHERE id = 1";
        //  4.获取执行SQL的对象 Statement
        Statement stmt = conn.createStatement();
        //  5.执行SQL
        int count = stmt.executeUpdate(sql);    //  受影响的行数
        //  6.处理结果
        System.out.println(count);
        //  7.释放资源
        stmt.close();
        conn.close();
    }
}

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JDBC API详解

DriverManager

Connection

public class JDBCDemo_Connection {
    public static void main(String[] args) throws Exception {
        //  1.注册驱动
        Class.forName("com.mysql.jdbc.Driver"); //  可以省略
        //  2.获取连接
        String url = "jdbc:mysql://127.0.0.1:3306/db1";
        String username = "root";
        String password = "8589";
        Connection conn = DriverManager.getConnection(url, username, password);
        //  3.定义SQL
        String sql1 = "UPDATE account set money = 3000 WHERE id = 1";
        String sql2 = "UPDATE account set money = 3000 WHERE id = 2";
        //  4.获取执行SQL的对象 Statement
        Statement stmt = conn.createStatement();
        try {
            //  开启事务
            conn.setAutoCommit(false);
            //  5.执行SQL
            int count1 = stmt.executeUpdate(sql1);    //  受影响的行数
            System.out.println(count1);
            int count2 = stmt.executeUpdate(sql2);    //  受影响的行数
            System.out.println(count2);
            //  提交事务
            conn.commit();
        } catch (SQLException e) {
            //  回滚事务
            conn.rollback();
            throw new RuntimeException(e);
        }
        //  7.释放资源
        stmt.close();
        conn.close();
    }
}

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数据库连接池