Handling a bunch of various requests into the database - php

Question

I currently have a php page that grabs information from a database and produces HTML with data attributes that are filled in by from the MySQL query. The database is going to be used to search, with many different options for searches.
What I need help with is knowing a way so to organize how the many variables are handled. It's a really big mess of code, and even with all the comments I put it gives me a headache trying to figure out how to add another variable to the search.
All the variables, except for the LIMIT to which row and how many results, are optional. So if someone leaves everything except that blank, I still want it to function as well as if they meticulously filled in all the fields.
Here's what I have, with 6 variables.
<?php
$product_size = "(".$_GET['size']." BETWEEN productsizeDOWN AND productsizeUP)"; // This code sets the variable to input into the MySQL string based on the URL
$product_size_check = $_GET['size']; // the _checks check are used to see if the value is or isn't empty using if statements below
$manufacturer = $_GET['manufacturer'];
$product_manufacterer_check = $_GET['manufacturer']; // _check
$product_invisible = "(hideproduct = '".$_GET['invisible']."')"; // Checks if product is hidden
$product_invisible_check = $_GET['invisible']; // _check
$product_instock_check = $_GET['instock']; // _check
$product_limit0 = $_GET['startat']; // This is the first number after LIMIT; the row to start in.
$product_limit1 = $_GET['results']; // This is how many results to load.
$manufacturer_array = explode(",", $manufacturer); // The manufacturer comes in as "Nike,Addidas,Rebok" and is turned into an array
$manufacturer_imploded = implode("' OR productmanufacturer = '", $manufacturer_array); // Puts it back together with "OR productmanufacturer =" between each name.
$product_manufacterer = ("(productmanufacturer = '".$manufacturer_imploded."')"); // formats it so it can be directly inserted into MySQL string with a WHERE in front.
if($product_invisible_check == ""){
$product_invisible = "";
}else{$where = "WHERE ";}; //Useless code that I havn't deleted that I tried to use when I searched the entire database
if($product_size_check == ""){
$product_size = "";
}else{$where = "WHERE ";};
if($product_manufacterer_check == ""){
$product_manufacterer = "";
}else{$where = "WHERE ";};
if($product_instock_check == "N"){
$product_instock = "(stockstatus <= '0' AND donotallowbackorders = 'Y') AND "; // Checks if product is in stock (Allowing backordering OR stock >1)
$where = "WHERE ";
}
elseif($product_instock_check == "Y") {
$product_instock = "(stockstatus > '0' OR donotallowbackorders = 'N') AND ";
$where = "WHERE ";
}
else {
$product_instock = "";
};
$sql="Select * FROM ioa7pd_Products WHERE ".$product_instock.$product_size."AND".$product_manufacterer_and.$product_manufacterer."".$product_invisible." LIMIT ".$product_limit0.", ".$product_limit1; // The end result of it all.
echo $sql;
?>
When the URL is
test.php?size=5&manufacturer=Nike,Addidas,Rebok&invisible=N&instock=Y&startat=0&results=30
the resulting SQL query is
Select * FROM ioa7pd_Products WHERE (stockstatus > '0' OR donotallowbackorders = 'N') AND (5 BETWEEN productsizeDOWN AND productsizeUP)AND(productmanufacturer = 'Nike' OR productmanufacturer = 'Addidas' OR productmanufacturer = 'Rebok')(hideproduct = 'N') LIMIT 0, 30
But I plan to add more options to the search.
My main question is simply: What way can I organize this to make it simple to add more variables? Tiered if statements?
Travesty has been helping me with my code and has really been great in organizing it.
Here is the current code. It needs to be secure to prevent injection.
// Database connection
$con = mysql_connect("[CENSORED]","[CENSORED]","[CENSORED]")
or die("Could not connect: " . mysql_error());
mysql_select_db("[CENSORED]") or die('Could not select database');
// Begin organization of URL variables into MYSQL Query
$get_size = $_GET['size'];
$get_manufacturer = $_GET['manufacturer'];
$get_invisible = $_GET['invisible'];
$get_instock = $_GET['instock'];
$get_sex = $_GET['sex'];
$get_startat = $_GET['startat'];
$get_results = $_GET['results'];
if ($get_size != ""){
$all_selectors[] = "(".$get_size." BETWEEN productsizeDOWN AND productsizeUP)"; // Add to array if size is not blank.
};
if ($get_manufacturer != ""){
$manufacturer_exploded = explode(",", $get_manufacturer);
$manufacturer_imploded = implode("' OR productmanufacturer = '", $manufacturer_exploded);
$all_selectors[] = ("(productmanufacturer = '".$manufacturer_imploded."')");
};
if ($get_invisible != ""){
$all_selectors[] = "(hideproduct = '".$get_invisible."')";
};
if($get_instock == "N" or $get_instock == "n"){
$all_selectors[] = "(stockstatus <= '0' AND donotallowbackorders = 'Y')";
}elseif($get_instock == "Y" or $get_instock == "y") {
$all_selectors[] = "(stockstatus > '0' OR donotallowbackorders = 'N')";
};
if ($get_startat != "" or $get_results != ""){
$number_results = "LIMIT ".$get_startat.", ".$get_results;
} else {
$number_results = "LIMIT 0, 15";
};
// All variables are now in an array, except "startat" and "results"
$all_selectors0 = "WHERE ".implode(" AND ", $all_selectors);
// Create SQL query
$sql="Select * FROM sadsads_Products ".$all_selectors0." ".$number_results;

Answer 1

I would do something more like this. It's not tested and probably not 100% complete...you may need to do some further customization, particularly with adding more special cases to the switch statement, but this will make adding more variables much easier:
REMOVED OLD EXAMPLE, SEE UPDATED EXAMPLE BELOW
One key thing to note is that you aren't sanitizing your database inputs. Your code is vulnerable to SQL injection. My example above helps to solve that, but this code isn't fully tested, so you should ensure that all user input is sanitized before using it in any query.
If your field names don't match up with your MySQL columns (which it looks like they don't), then you can fix them with an associative array:
$columns = array(
// [form field] => [mysql column]
'size' => 'product_size',
'manufacturer' => 'product_manufacturer',
'invisible' => 'hideproduct'
// ...
);
And then in your switch statement, do something more like this:
$whereClause[] = "{$columns[$key]} = '{$value}'";
FINAL UPDATE:
DOCUMENTED SAMPLE - has plenty of comments and extra stuff to make it work on Codepad
EXACT WORKING CODE - you should be able to copy and paste this (and add your DB credentials) and it should work:
$con = mysqli_connect("[CENSORED]", "[CENSORED]", "[CENSORED]") or die("Could not connect: ". mysqli_error());
mysqli_select_db("[CENSORED]") or die("Could not select database");
$columns = array(
'size' => 'product_size',
'manufacturer' => 'product_manufacturer',
'invisible' => 'hideproduct'
);
$whereClause = array();
$limit = array("startat" => 0, "results" => 15);
foreach ($_GET as $key=>$value) {
$key = mysqli_real_escape_string($key);
if (is_array($value)) {
for ($i = 0; $i < count($value); $i++) {
$value[$i] = mysqli_real_escape_string($value[$i]);
}
} else {
$value = mysqli_real_escape_string($value);
}
switch ($key) {
case 'size':
$whereClause[] = "({$value} BETWEEN productsizeDOWN AND productsizeUP)";
break;
case 'startat':
case 'results':
$limit[$key] = $value;
break;
case 'instock':
$whereClause[] = "(stockstatus ". ($value == 'N' ? "<=" : ">") ." '0' ". ($value == 'N' ? "AND" : "OR") ." donotallowbackorders = '". ($value == 'N' ? "Y" : "N") ."')";
break;
default: {
if (is_array($value)) {
$whereClause[] = "{$columns[$key]} IN ('". implode("', '", $value) ."')";
} else {
$whereClause[] = "{$columns[$key]} = '{$value}'";
}
}
}
}
$sql = "SELECT * FROM ioa7pd_Products". (empty($whereClause) ? "" : " WHERE ". implode(" AND ", $whereClause)) ." LIMIT {$limit['startat']}, {$limit['results']}";
echo $sql;

Answer 2

after
else {
$product_instock = "";
};
do:
$limit = '';
if( !empty($product_limit0) && !empty($product_limit1) )
$limit = " LIMIT $product_limit0, $product_limit1";
$sql="Select * FROM ioa7pd_Products WHERE ".$product_instock.$product_size."AND".$product_manufacterer_and.$product_manufacterer."".$product_invisible." $limit"; // The end result of it all.
echo $sql;
If you have separate params in $_GET, you would have to traverse with multiple if statements. you can pass the params as an array into $_GET, with numeric keys, that would help a bunch.