database problems with php - php

Question

I am trying to insert a row into my data base, but what ever i seem to do I am always getting an error.
Sometimes I get parse errors and sometimes I get column errors.
Here is my code.
Thanks in advance.
<?php
include_once('config.php');
$asin = $_POST['asin'];
// $title = "<script>document.write(title)</script>";
// $mpn = "<script>document.write(mpn)</script>";
// $price = "<script>document.write(price)</script>";
$sql = "INSERT INTO `amazon`.`amazon` (`asin`, `title`, `mpn`, `price`) VALUES ($asin, "test", 1, 2)";
// $sql = 'INSERT INTO amazon'.
// '(asin, title, mpn,price) '.
// 'VALUES ('{$asin},' "test", 1, 2)';
mysql_select_db('amazon');
$retval = mysql_query( $sql, $conn );
if(! $retval ) {
die('Could not enter data: ' . mysql_error());
}
echo "Entered data successfully\n";
?>

Answer 1

You need to use '' against your variable $asin as:
$sql = "INSERT INTO `amazon`.`amazon` (`asin`, `title`, `mpn`, `price`) VALUES ('".$asin."', 'test', 1, 2)";

Answer 2

Note:-
You can't use double quotes in double quotes. Replace double
quote(") with single quote(') around test value.
use variables in single quotes.(Example - $asin to '$asin')
Replace your query with this:-
$sql = "INSERT INTO `amazon`.`amazon` (`asin`, `title`, `mpn`, `price`) VALUES ('$asin', 'test', 1, 2)";

Answer 3

You have made two mistakes. in
$sql = "INSERT INTO `amazon`.`amazon` (`asin`, `title`, `mpn`, `price`) VALUES ($asin, "test", 1, 2)";
$asin and "test".
if $asin is an integer value always THEN it's okay otherwise you have to write it '".$asin."'
and for "test" the error is the comma you use here (") because you query is starting with same (") comma, so when you put same comma before test then query ends here and give you error. So replace this comma by (').
replace "test" by 'test'.
Now correct query is -
$sql = "INSERT INTO `amazon`.`amazon` (`asin`, `title`, `mpn`, `price`) VALUES ('".$asin."', 'test', 1, 2)";