JDBCSQL语句判断账号密码是否正确

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

   

public class TestJDBC {

    public static void main(String[] args) {

        try {

            Class.forName("com.mysql.jdbc.Driver");

        } catch (ClassNotFoundException e) {

            e.printStackTrace();

        }

 

        try (Connection c = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/how2java?characterEncoding=UTF-8",

                "root", "admin");

                Statement s = c.createStatement();

                 

                ) {

            String name = "dashen";

            //正确的密码是：thisispassword

            String password = "thisispassword1";

   

            String sql = "select * from user where name = '" + name +"' and password = '" + password+"'";

              

            // 执行查询语句，并把结果集返回给ResultSet

            ResultSet rs = s.executeQuery(sql);

              

            if(rs.next())

                System.out.println("账号密码正确");

            else

                System.out.println("账号密码错误");

             

        } catch (SQLException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

   

    }

}

3. SQL语句判断账号密码是否正确

判断账号密码的正确方式是根据账号和密码到表中去找数据，如果有数据，就表明密码正确了，如果没数据，就表明密码错误。

不恰当的方式 是把uers表的数据全部查到内存中，挨个进行比较。 如果users表里有100万条数据呢？ 内存都不够用的。