为什么小弟我不会写代码

为什么我不会写代码？

 添加考试

php代码：

if($_GET['do']=='add'){<br />    include DedeInclude('templets/student/student_voice_add.htm');<br />	$id = $_POST['username'];<br />	$email = $_POST['email'];<br />	$content = $_POST['content'];<br />	$time = date('Y-m-d H:i:s');<br />	$category = $_POST['category'];<br />	$flag = $_POST['flags'];<br />	$flags=implode(",",$flag);<br />	$checked = $_POST['checked'];<br />	//echo $id."<br />".$email."<br />".$content."<br />".$time."<br />".$category."<br />".$flags."<br />".$checked;<br />	$sql = "INSERT INTO djs_skstudent_voice (username ,content ,time ,category ,checked ,email ,flag)VALUES ('$id','$content', '$time' , '$category', '$checked','$email','$flags')";<br />	$dsql->ExecuteNoneQuery($sql);

倒是能够添加。但是他会添加一个所有值为空白的。然后才是自己想要添加的。就是说他会先执行一次所有值为空的sql。这是咋回事？