Mysql parameterized queries in php - php

Question

I have a php code for some MYSQL interogations,
Code is:
$DBTYPE = 'mysql';
$DBHOST = 'localhost';
$DBUSER = 'tuser';
$DBPASSWORD = 'password';
$DBNAME = 'dbname';
$link = mysql_connect($DBHOST, $DBUSER, $DBPASSWORD);
mysql_select_db($DBNAME);
if (!$link) {
die('Could not connect: ' . mysql_error());
}
//IMG**0**
$hotelc = $hotelCodes[**0**];
$result = mysql_query("SELECT ImageURL FROM Flat_table where HotelCode= '$hotelc'", $link);
if(!$result) {
die("Database query failed: " . mysql_error());
}
while ($row = mysql_fetch_array($result)) {
$ImageURL**0** = $row["ImageURL"];
}
//IMG**1**
$hotelc = $hotelCodes[**1**];
$result = mysql_query("SELECT ImageURL FROM Flat_table where HotelCode= '$hotelc'", $link);
if(!$result) {
die("Database query failed: " . mysql_error());
}
while ($row = mysql_fetch_array($result)) {
$ImageURL**1** = $row["ImageURL"];
}
..........................
//IMG**x**
$hotelc = $hotelCodes[**x**];
$result = mysql_query("SELECT ImageURL FROM Flat_table where HotelCode= '$hotelc'", $link);
if(!$result) {
die("Database query failed: " . mysql_error());
}
while ($row = mysql_fetch_array($result)) {
$ImageURL**x** = $row["ImageURL"];
}
The repeating value on each code line is bolded.
How can i create a Mysql parameterized queries in php.n to avoid write all the lines .I need to extract ~100 $ImageURL from the Flat_table where the $hotelc is found.

Answer 1

For example you have to repeat it $N times:
for($i=0; $i<$N; $i++)
{
$hotelc = $hotelCodes[ $i ];
$result = mysql_query("SELECT ImageURL FROM Flat_table where HotelCode= '$hotelc'", $link);
if(!$result) {
die("Database query failed: ".mysql_error());
}
while ($row = mysql_fetch_array($result)) {
${'ImageURL'+$i} = $row["ImageURL"];
}
}

Answer 2

To loop, use for:
for($n=0; $n<100; $n++){
$hotelc = $hotelCodes[$n];
$result = mysql_query("SELECT ImageURL FROM Flat_table where HotelCode= '$hotelc'", $link);
if(!$result) {
die("Database query failed: " . mysql_error());
}
while ($row = mysql_fetch_array($result)) {
$ImageURL[$n] = $row["ImageURL"];
}
}
But the inner functions inside the loop is inefficient because mysql query will be executed 100 times. You can query all the ImageURL by using IN() syntax in mysql:
//Wrap all hotelCodes into one string for query, like ["a","b"] to "'a','b'"
$len = count($hotelCodes);
foreach($hotelCodes as $key=>$code){
$hotelCodes[$key] = "'".$code."'";
}
$codesStr = implode(",", $hotelCodes);
$result = mysql_query("SELECT ImageURL FROM Flat_table where HotelCode IN (".$codeStr.")", $link);
//Other things...

Answer 3

When writing a function, you look for the commonality. Furthermore, you want to minimize the database interaction. I am, for the sake of deprecation, going to assume $link uses mysqli_connect()
$ImageURL = array();
$list = implode('", "', $hotelCodes);
$result = mysqli_query($link, 'SELECT ImageURL FROM Flat_table where HotelCode IN "' . $list . '"');
while($row = mysql_fetch_assoc($result)) {
$ImageURL[] = $row["ImageURL"];
}
This runs only one query and then loops through the results, generating an associative array. So echo $ImageURL[0]; will output your first URL.