Java读取SQL server数据库

要打开SQL server 的三个服务，然后再执行代码。

package com.sql;

import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;

public class demo {
    public static void main(String[] args) {
        String user = "sa";
        String password = "root";
        Connection conn;
        Statement stmt;
        ResultSet rs;
//        String url = "jdbc:sqlserver://127.0.0.1:1433;DatabaseName=student_db;";

        String url = "jdbc:sqlserver:DESKTOP-I8G440K/SQLEXPRESS:1433;DatabaseName=master";
        String sql = "select * from dbo.MSreplication_options";
        try {
            // 连接数据库
            conn = DriverManager.getConnection(url, user, password);
            // 建立Statement对象
            stmt = conn.createStatement();
            // 执行数据库查询语句
//            rs = stmt.executeQuery(sql);
//            while (rs.next()) {
//                String id = rs.getString("s_id");
//                String name = rs.getString("S_name");
//                float score = rs.getFloat("s_score");
//                String sex = rs.getString("s_sex");
//               System.out.println("学号 "+id+"姓名 "+name+"成绩 "+score+"性别 "+sex);
//            }
//            if (rs != null) {
//                rs.close();
//                rs = null;
//            }
//            if (stmt != null) {
//                stmt.close();
//                stmt = null;
//            }
//            if (conn != null) {
//                conn.close();
//                conn = null;
//            }
        } catch (SQLException e) {
            e.printStackTrace();
            System.out.println("数据库连接失败");
        }
    }
}