Query was empty PHP error

问题

I am trying to build a cart using MySQL. I keep getting this error 'Query was empty' when I run this code. Please help I've tried several things such as putting the variables inside the string instead of concatenating it.

<?php ob_start(); ?><?php require_once("../include/membersite_config.php"); ?>
<?php 
    require('../products_reloaded/config.php');
    session_start();

            $user = $_REQUEST['user'];
            $user = mysql_real_escape_string($user);
            $itemNum = $_REQUEST['itemNum'];
            $itemNum = mysql_real_escape_string($itemNum);
            $quantity = $_POST['quantity'];
            $quantity = intval($quantity);
            $CheckForExistence = mysql_query("select * from cart where user = '$user' and p_number = '$itemNum'" );
            $alreadyExistsChecker = mysql_num_rows($CheckForExistence);
            if($alreadyExistsChecker >= 1)
            {
                $quantity +=1;
                echo "this is equal to $alreadyExistsChecker";
            }

            if($alreadyExistsChecker == 0)
            {
                $getQuery = mysql_query("select * from product where p_number = '$itemNum'");


                while($row = mysql_fetch_array($getQuery))
                {
                    $name = $row['p_name'];
                    $image = $row['p_url'];
                    $price = $row['p_price'];
                }
                $name = mysql_real_escape_string($name);
                $image = mysql_real_escape_string($image);
                $price = intval($price);
                $query = mysql_query('insert into cart values('.$user.','.$itemNum.','.$name.', '.$image.','.$quantity.', '.$price.')'); 
                $result = mysql_query($query);
                if (!$result) {
                    print "An error occured: " . mysql_error() . "\n";
                }

            }

            header('http://www.definitionxjm.com/shopping/viewCart.php');



?>

回答1:

What do you try to achieve with this line?

$result = mysql_query($query);

Just delete it and change the line above to

$result = mysql_query('insert into cart values('.$user.','.$itemNum.','.$name.', '.$image.','.$quantity.', '.$price.')');

[Edit]

Btw. you are forgetting the " (quotes) inside the query which causes an sql error to occur, leading to $query = false (see manual). $query (false) then gets converted to string, resulting in '' (an empty string) which you pass to mysql_query and that generates an "Query was empty"-Message, as it should because you tried to send an empty query.

回答2:

It can also mean the table which is in consideration is empty.This condition arises when the "DELETE FROM table_name where ;" is used. Here if the table "table_name" has no data, it cannot delete anything and hence it shows an error stating that the query is empty.

来源：https://stackoverflow.com/questions/16500901/query-was-empty-php-error

标签

php

mysql

e-commerce