import java.sql.*;

public class sql1 {
    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://127.0.0.1:3306/111?characterEncoding=UTF-8",
                "root", "1234");
             Statement s = c.createStatement();
        ) {
            String name = "lisi";
            String password = "345";

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

            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) {
            e.printStackTrace();
        }
    }
}

数据库的表如下

当用户名和密码正确时，输出“账号密码正确”

当用户名和密码错误时，输出“账号密码错误”