SQL查询中的多个PHP变量

Question

Im struggling to understand quotes in PHP Mainly when doing SQL Query's. I keep getting an error on this query.

SELECT Hotels.HotelImage1, Holidays.ID, Hotels.HotelName, Destinations.Name, PriceBands.PriceBand_Cost FROM Holidays
INNER JOIN Hotels ON Holidays.Hotel_ID = Hotels.ID
INNER JOIN PriceBands ON Holidays.PriceBand_ID = PriceBands.ID
INNER JOIN Destinations ON Destinations.ID = Holidays.Destination_ID
WHERE Destinations.ID = ".$dest."AND Hotels.ID =".$hotel;

I'm Trying to use two PHP variables in the query. Any help would be greatly appreciate.

Answer 1

Your query should be

$query = "SELECT Hotels.HotelImage1, Holidays.ID, Hotels.HotelName, Destinations.Name, PriceBands.PriceBand_Cost FROM Holidays
INNER JOIN Hotels ON Holidays.Hotel_ID = Hotels.ID
INNER JOIN PriceBands ON Holidays.PriceBand_ID = PriceBands.ID
INNER JOIN Destinations ON Destinations.ID = Holidays.Destination_ID
WHERE Destinations.ID = '$dest' AND Hotels.ID = '$hotel'";

Since you are using ID and if it is an integer field, it is not required to put quotes around ID value, you can also do

$query = "SELECT Hotels.HotelImage1, Holidays.ID, Hotels.HotelName, Destinations.Name, PriceBands.PriceBand_Cost FROM Holidays
INNER JOIN Hotels ON Holidays.Hotel_ID = Hotels.ID
INNER JOIN PriceBands ON Holidays.PriceBand_ID = PriceBands.ID
INNER JOIN Destinations ON Destinations.ID = Holidays.Destination_ID
WHERE Destinations.ID = $dest AND Hotels.ID = $hotel";

UPDATE:

You need to escape the query input. You can esacpe the user input using two methods. Using mysqli_real_escape_string or using prepared statements :

With mysqli_real_escape :

$dest  = $mysqli->real_escape_string($dest);
$hotel = $mysqli->real_escape_string($hotel);

$stmt = "SELECT Hotels.HotelImage1, Holidays.ID, Hotels.HotelName, Destinations.Name, PriceBands.PriceBand_Cost FROM Holidays
    INNER JOIN Hotels ON Holidays.Hotel_ID = Hotels.ID
    INNER JOIN PriceBands ON Holidays.PriceBand_ID = PriceBands.ID
    INNER JOIN Destinations ON Destinations.ID = Holidays.Destination_ID
    WHERE Destinations.ID = '$dest' AND Hotels.ID = '$hotel'";

With Prepared statement :

$stmt = $mysqli->prepare("SELECT Hotels.HotelImage1, Holidays.ID, Hotels.HotelName, Destinations.Name, PriceBands.PriceBand_Cost FROM Holidays
    INNER JOIN Hotels ON Holidays.Hotel_ID = Hotels.ID
    INNER JOIN PriceBands ON Holidays.PriceBand_ID = PriceBands.ID
    INNER JOIN Destinations ON Destinations.ID = Holidays.Destination_ID
    WHERE Destinations.ID = ? AND Hotels.ID = ?");

/* Bind parameters. Types: s = string, i = integer, d = double,  b = blob */
$stmt->bind_param("ii", $dest, $hotel);

Answer 2

Try change last string to

WHERE Destinations.ID = '".$dest."' AND Hotels.ID ='".$hotel."'";

And always show sql errors. It is helpfull

Answer 3

SQL (Most flavours, anyways) requires that strings be delimited by single-quotes. You have to build this into your query. Also, don't bother concatenating the variables as PHP is capable of finding variables inside strings.

Answer 4

Do not build SQL queries that way. Use Prepared Statements instead. Its parameter bind avoids any issue related to the data-type, SQL injection attacks and any security stuff.

http://php.net/manual/en/mysqli.quickstart.prepared-statements.php