比较两个下拉列表中的两个不同年份，如果第一年高于第二年，则回显一条消息

Question

I want to check that if I have in my first drop down list the year is 2001 and in the second dropdown list i select 1900 as the year then I will echo a message to the user that he should select a year that the first is lower than the second (ex: 2001<2002) and if it has that error then it should store the data in my database until he change it.

My code to update the database is the below....

if(isset($_POST['id'])){

        $id = $_POST['id'];
        $school = mysql_real_escape_string($_POST["school"]);
        $degree = mysql_real_escape_string($_POST["degree"]);
        $website = mysql_real_escape_string($_POST["website"]);
        $start_date = mysql_real_escape_string($_POST["start_date"]);
        $end_date = mysql_real_escape_string($_POST["end_date"]);
        $start_year = mysql_real_escape_string($_POST["start_year"]);
        $end_year = mysql_real_escape_string($_POST["end_year"]);
        $degree_description = mysql_real_escape_string($_POST["degree_description"]);

        $query="UPDATE education
                SET school = '$school', degree = '$degree', website = '$website', start_date='$start_date', end_date='$end_date', start_year='$start_year', end_year='$end_year', degree_description='$degree_description'
                WHERE id='$id' AND username='$username'";

        mysql_query($query)or die(mysql_error());
        if(mysql_affected_rows()>=0){
            echo "<p>($username) Record Updated<p>";
        }else{
            echo "<p>($username) Not Updated<p>";
        }
    }

    else{
      //first time, initialize as you wish. Probably need to get the first id for this user, using another query
      $id = 0;
    }

and i guess that my code in order to check the years is this ...

if($start_year>$end_year)
{
    echo "The error Message";
}

But I cant find where i should place it in order to work correctly

Answer 1

Something like this? It's entirely up to you though really. I am making the assumption that if you are showing the error you do NOT want to update the database

if(isset($_POST['id'])){

    $id = $_POST['id'];
    $school = mysql_real_escape_string($_POST["school"]);
    $degree = mysql_real_escape_string($_POST["degree"]);
    $website = mysql_real_escape_string($_POST["website"]);
    $start_date = mysql_real_escape_string($_POST["start_date"]);
    $end_date = mysql_real_escape_string($_POST["end_date"]);
    $start_year = mysql_real_escape_string($_POST["start_year"]);
    $end_year = mysql_real_escape_string($_POST["end_year"]);
    $degree_description = mysql_real_escape_string($_POST["degree_description"]);

    if($start_year > $end_year){
        echo 'The error Message';
        $good = false;
    }else{
        $good = true;
    }

    if($good == true){

        $query="UPDATE education
                SET school = '$school', degree = '$degree', website = '$website', start_date='$start_date', end_date='$end_date', start_year='$start_year', end_year='$end_year', degree_description='$degree_description'
                WHERE id='$id' AND username='$username'";


        mysql_query($query)or die(mysql_error());
        if(mysql_affected_rows()>=0){
            echo "<p>($username) Record Updated<p>";
        }else{
            echo "<p>($username) Not Updated<p>";
        }
    }   
}
else
{
    //first time, initialize as you wish. Probably need to get the first id for this user, using another query
    $id = 0;
}