Executing PHP Function When a Form Submit is Clicked

Question

I am having trouble understanding handling variables that are passed through pages when a form submit button is clicked. Basically i have a text area where a user writes an sql query. Then clicks submit. Then on the same page (x.php) , i have to display the results in a table. I figured, when the user clicks the button, i call a function that connects to the database, then runs the query, and outputs the result in a table. The code i have below is a mock, and isnt quite working.But above is essentially what i am trying to do.

In my code, I call the page, and check to see if the proper submit button has been clicked, is that how i am suppose to do it?

Also, I am trying to post the metadata in the code below, but how does the table replace what is already on the page?

<html>
<head> 
<title>CNT 4714 - Project Five Database Client</title>
</head>
<body style="background-color:white">
<center>
<h1 style="color:red">CNT 4714 - Project Five Database Client</h1>
<hr>
<div style="float:left; text-align:left;padding-right:80px; padding-left:80px; ">
<font color="yellow">
<?php

?>
Welcome Back!<br>
<?php echo $_POST["user"];?>
  </font>
</div>
<font color="yellow">
<div style="float:left; text-align:left">
<center>
<h2 style="color:green">Enter Query</h2><br><br>
Please enter a valid SQL Query or update statement. You may also just press<br>
"Submit Query" to run a defualt query against the database!
<form action="" id="sql" method="post">
<br>
  <textarea rows="10" cols="50" name="query" form="sql">Enter text here...</textarea><br><br>
  <input type="submit" name="submit" color="red">
  <input type="submit" name="" color="red" value="Submit Update">
</form>
<?php

if(isset($_POST['submit'])){
    echo "hello";
   query(); //here goes the function call
}
function query()
{
    echo "hello";
    $conn = mysqli_connect("localhost:3306", "root", "*******", "project4");
    $query = $_POST["query"];
    $result = mysqli_query($conn, $query);
    $metadata = mysqli_fetch_fields($result);
    print("<tr>");
    for($i=0; $i<count($metadata);$i++){
        print("<tr");
        printf("%s",$metadata[$i]->name);
        print("</tr>");
    }
}


?>
</center>
</div>
</font>
</center>

</body>
</html>

Give a name to the submit button as submit and in form tag add method="POST". — Balraj Allam
– Balraj Allam, Commented Dec 1, 2016 at 6:45

N. Hamelink · Accepted Answer · 2016-12-01 06:57:00Z

2

You are trying to get the values of the global variable $_POST while you are posing it to $_GET. The way to fix this is assigning the method into your form element.

Example:

<form id="sql" action="" method="POST">

There are many ways for checking or the form is submitted, one of this ways (the one I am always using) is checking or the $_SERVER['REQUEST_METHOD'] is equal to "POST". This way you can tell the different between a GET, POST, or PUT request.

Example:

if($_SERVER['REQUEST_METHOD'] == 'POST')
{
    if(isset($_POST['sql']))
    {
        ....
    }
}

answered Dec 1, 2016 at 6:57

N. Hamelink

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4 Comments

Walter Yaesu Over a year ago

ok thanks, I have updated the code to what i have now, and i cant seem to get the data to print. I got the sql query to run without an error, what could i be doing wrong?

M. Eriksson Over a year ago

Why not just if (isset($_POST['sql']))? It won't be set if it isn't a post request.

Walter Yaesu Over a year ago

i used that and it works. But i used the name of the button, since i have multiple buttons. DevNiels said there are many ways to do it. I guess his way is one way of doing it.

N. Hamelink Over a year ago

@MagnusEriksson Like I said in my post, there are many ways to do it, I like this way because I can check or there is a request sent whitch tells me someone is sending data. I am also able to sort out or it's a GET, POST or PUT request.

josephting · Accepted Answer · 2016-12-01 06:46:37Z

0

If you're using $_POST, your form request method should be POST.

<form action="" id="sql" method="post">

Otherwise, it will submit it with a GET request by default.

In that case, you will have to access the variable using $_GET instead.

answered Dec 1, 2016 at 6:46

josephting

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