PHP form not writing to mySQL database - php

Question

I'm just learning PHP and am trying the most basic thing: capturing info from a form and sticking it into a table in a mySQL database. I'm embarrassed to ask such a stupid newbie question, but after reviewing two books, several Stack Overflow posts, and 7 different tutorials, I still can't get my pathetic code to write a few lousy metrics to my database.
Here's the latest version of the code. Could someone please tell me what I am doing wrong?
* Basic HTML Form *
<form method="post" action="post_metrics_stack.php" >
<p>Date<br />
<input name="date" type="text" /></p>
<p>Metric1<br />
<input name="metric1" type="text" /></p>
<p>Metric2<br />
<input name="metric2" type="text" /></p>
<input type="submit" name="submit" value="Submit" />
</form>
* Processor File *
<?php
$date=$_POST['date'];
$metric1=$_POST['metric1'];
$metric2=$_POST['metric2'];
$con = mysql_connect("localhost", "root", "mypassword");
if (!$con)
{die('Could not connect to mysql: ' . mysql_error());}
$mydb = mysql_select_db("mydatabasename");
if (!$mydb)
{die('Could not connect to database: ' . mysql_error());}
mysql_query("INSERT INTO my_metrics VALUES ('$date', '$metric1', '$metric2')");
Print "Your metrics have been successfully added to the database.";
mysql_close($con);
?>

Answer 1

Your mysql-syntax is wrong.
Try
INSERT INTO my_metrics
SET
date = '$date',
metric1 = '$metric1',
metric2 = '$metric2'

Answer 2

Depending on what the table looks like, your code may or may not work,
"INSERT INTO my_metrics VALUES ('$date', '$metric1', '$metric2')"
assumes that the fields are in that order, and that there are no fields before this one.
"INSERT INTO my_metrics (date, metric1, metric2) VALUES ('$date', '$metric1', '$metric2')"
would be more future proof, and may also solve your problem as they are going to insert into the correct fields.
It is also possible that you are getting some bad data for the field definitions, try doing the insert in phpmyadmin or at the command line instead of in php, then work backwards from there.

Answer 3

As far as the vulnerability to SQL injection, you should feed your input strings to mysql_real_escape_string();. This will escape any unwanted characters.
When connecting to the database, you write
$con = mysql_connect("localhost", "root", "mypassword");
if (!$con)
{die('Could not connect to mysql: ' . mysql_error());}
You can simplify this, and making this more readable by writing
mysql_connect('localhost','root','mypassword') or die('Could not connect to mysql:<hr>'.mysql_error());
For solving your problem, see if specifieng column names helps. If you don't, mysql will assume you enter values in the order of the columns, you might get some trouble with an ID field, or something like that. Your query could look like this:
"INSERT INTO my metrics (date,metric1,metric2) VALUES ('$data','$metric1','$metric2'))"
And finally, here's a speed concideration.
There are two ways to write strings: using single quotes ('string'), and using double quotes ("string"). in the case of 'string' and "string", they will work exactly the same, but there is a difference. Look at the following code
$age=3
echo 'the cat is $age years old.';
//prints out 'the cat is $age years old.'
echo "the cat is $age years old.";
//prints out 'the cat is 3 years old'
echo 'the cat is '.$age.' years old';
//prints out 'the cat is 3 years old'.
As you can see from this example, when you use single quotes, PHP doesn't check the string for variables and other things to parse inside the string. Doing that takes PHP longer than concatinating the variable to the string. so although
echo "the cat is $age years old"
is shorter to type than
echo 'the cat is '.$age.' years old';
it will boost your page loading when you write larger applications.

Answer 4

Hooray! Hooray! Hooray!
Thank you all for such helpful advice! It finally works! Here's the updated code in case any other newbies have the same issue. (Hope I didn't screw anything else up.)
Form
<form method="post" action="post_metrics_stack.php" >
<p>Date<br />
<input name="date" type="text" /></p>
<p>Metric1<br />
<input name="metric1" type="text" /></p>
<p>Metric2<br />
<input name="metric2" type="text" /></p>
<input type="submit" name="submit" value="Submit" />
</form>
Processor
<?php
ini_set('display_errors', 1); error_reporting(E_ALL);
// 1. Create connection to database
mysql_connect('localhost','root','mypassword') or die('Could not connect to mysql: <hr>'.mysql_error());
// 2. Select database
mysql_select_db("my_metrics") or die('Could not connect to database:<hr>'.mysql_error());
// 3. Assign variables (after connection as required by escape string)
$date=mysql_real_escape_string($_POST['date']);
$metric1=mysql_real_escape_string($_POST['metric1']);
$metric2=mysql_real_escape_string($_POST['metric2']);
// 4. Insert data into table
mysql_query("INSERT INTO my_metrics (date, metric1, metric2) VALUES ('$date', '$metric1', '$metric2')");
Echo 'Your information has been successfully added to the database.';
print_r($_POST);
mysql_close()
?>

Answer 5

Here you go love :) try W3c it a good place for new pepps
<?php
$con = mysql_connect("localhost","peter","abc123");
if (!$con)
{
die('Could not connect: ' . mysql_error());
}
mysql_select_db("my_db", $con);
$sql="INSERT INTO my_metrics (date, metric1, metric2)
VALUES
('$_POST[date]','$_POST[mertric1]','$_POST[metric2]')";
if (!mysql_query($sql,$con))
{
die('Error: ' . mysql_error());
}
echo "Your metrics have been successfully added to the database.";
mysql_close($con)
?>