关于jsp访问mysql数据库的一些问题

发布于 2020-01-08 15:23:06

index.jsp
<body>

<form action="check.jsp" method="post">
    用户名<input type="text"  name="uname"><br/>
    密码<input type="password" name="upwd"><br/>
    <input type="submit"   value="登录"><br/>
</form>

</body>

check.jsp
// 导入驱动，加载具体驱动类

    Class.forName("com.mysql.cj.jdbc.Driver");
    // 与数据库建立连接
    connection = DriverManager.getConnection(URL, USERNAME, PSW);
    // 发送sql，执行增、删、改
    stmt = connection.createStatement();
    String name=request.getParameter("uname");
    String pwd=request.getParameter("upwd");

    //错误写法1：//String sql = "select count(*) from user where name=' "+name+" '  and  pwd=' "+pwd+" ' "; 

    String sql = "select count(*) from user where uname=' "+name+" '  and  upwd=' "+pwd+" ' ";
    //  =左边的uname是数据库中定义的字段名，右边的name是上面的String name获取的用户输入的值

    //错误写法2：//String sql = "select name,pwd from user where name='name'  and  pwd='pwd' ";