bind_param for php pdo for select - php

i have created delete statement in php pdo. i need to know bind_param query for my code. I used one bind_param which is not wrking.
PHP7
public function deleteRecord($table,$pk,$id){
if($table == "categories"){
$pre_stmt = $this->con->prepare("SELECT ".$id." FROM categories WHERE parent_cat = ?");
$pre_stmt->bind_param("i",$id);
$pre_stmt->execute();
$result = $pre_stmt->get_result() or die($this->con->error);
if ($result->num_rows > 0) {
return "DEPENDENT_CATEGORY";
}else{
$pre_stmt = $this->con->prepare("DELETE FROM ".$table." WHERE ".$pk." = ?");
$pre_stmt->bind_param("i",$id);
$result = $pre_stmt->execute() or die($this->con->error);
if ($result) {
return "CATEGORY_DELETED";
}
}


I rectified that above and got error on below
public function getAllRecord($table){
$result = $this->con->prepare("SELECT * FROM ".$table);
$result->execute();
$results = $result->fetchAll();
$rows = array();
if ($results->rowCount > 0) {
while($row = $results->fetch(PDO::FETCH_ASSOC)){
$rows[] = $row;
}
return $rows;
}
return "NO_DATA";
}
Error:Notice: Trying to get property of non-object in C:\xampp\htdocs\inv_project\public_html\includes\DBOperation.php on line 68

Related

PHP MYSQLI Query is failing

When trying to run a MYSQLI command in PHP, Its coming back failing.
function DB_query($query, $params = []) {
$conn = DB_connect();
if ($params)
{
$stmt = $conn->prepare($query);
$types = str_repeat('s', count($params));
$stmt->bind_param($types, ...$params);
$stmt->execute();
$result = $stmt->get_result();
} else {
$result = mysqli_query($conn, $query);
}
if ($result)
{
$result = mysqli_fetch_all($result);
return $result;
} else {
return mysqli_affected_rows($conn);
}
}
Here is my query:
DB_query("SELECT count(*) FROM members WHERE email = ? LIMIT 1",[$email])
It runs on:
$result = mysqli_fetch_all($result);
The results from $result: array(1)([0]=>array(1)([0]=>(int)1))
Here is my query:
DB_query("SELECT id, username, password FROM members WHERE email = ? LIMIT 1",[$email]);
It runs on:
$result = mysqli_fetch_all($result);
The results from $result: > array(0)
I have tried changing out the "mysqli_fetch_all" to fetch_all, but I cant figure it out. I need both query to run through the same function.
I cant figure out why the last query is returning nothing in the array.

<?php
$sql = "SELECT * FROM members WHERE email = '".$email."'";
$result = mysqli_query($con, $sql);
while($row = mysqli_fetch_row($result)) {
echo $row[0];
echo $row[1];
echo $row[2];
}
?>
Alternatively, you can use mysqli_fetch_array and use $row['fieldname'] inside the loop.

Why PHP function is returning Only the one row from mysql

I am fetching data from MYSQL database and Looping through the result but its returning only one row !!! can any one explain what's wrong
function getAll()
{
global $con;
$SQL = "SELECT * FROM users";
$stmt = $con->query($SQL);
if($stmt->num_rows > 0){
while($row = $stmt->fetch_row())
{
return $row;
}
}
}

The return should be outside the while loop !
Here is how you can get all the rows :
function getAll()
{
global $con;
$SQL = "SELECT * FROM users";
$stmt = $con->query($SQL);
if($stmt->num_rows > 0){
$arr = array();
while($row = $stmt->fetch_row())
{
$arr[] = $row;
}
return $arr;
}
}
Or you can do something like this return a generator and loop through :
function getAll()
{
global $con;
$SQL = "SELECT * FROM users";
$stmt = $con->query($SQL);
if($stmt->num_rows > 0){
while($row = $stmt->fetch_row())
{
yield $row;
}
}
}
see the result here !
echo '<pre>';
foreach (getAll() as $value) {
print_r($value);
}

Once you hit a return statement all execution of that function stops. You cannot return multiple times.
You can either return an array of all rows:
function getAll()
{
global $con;
$SQL = "SELECT * FROM users";
$stmt = $con->query($SQL);
if($stmt->num_rows > 0) {
while($row = $stmt->fetch_row())
{
$array[] = $row;
}
return $array;
}
}
Or use it as a generator (probably not what you want):
function getAll()
{
global $con;
$SQL = "SELECT * FROM users";
$stmt = $con->query($SQL);
if($stmt->num_rows > 0){
while($row = $stmt->fetch_row())
{
yield $row;
}
}
}

Fatal error: Call to a member function execute() on boolean in C:\xampp\htdocs\templa\v-includes\class.DAL.php on line 63

Have been trying all possible means to locate why it still showing fetal error but it keeps bouncing me back......
here is were am get the error
function getValue_where($table_name,$value,$row_value,$value_entered)
{
try{
$query = $this->link->query("SELECT $value from $table_name where $row_value='$value_entered'");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
Here is the full snipet of the code................
<?php
//include class library of database connecton
include 'class.database.php';
class ManageContent_DAL
{
public $link;
//construct function
function __construct()
{
$db_Connection = new dbConnection();
$this->link = $db_Connection->connect();
return $this->link;
}
function getValue($table_name,$value)
{
$query = $this->link->query("SELECT $value from $table_name");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
function getValue_descending($table_name,$value)
{
$query = $this->link->query("SELECT $value from $table_name ORDER BY `id` DESC");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
function getValue_distinct($table_name,$value)
{
$query = $this->link->query("SELECT DISTINCT $value from $table_name");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
function getValue_where($table_name,$value,$row_value,$value_entered)
{
try{
$query = $this->link->query("SELECT $value from $table_name where $row_value='$value_entered'");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
catch(Exception $e)
{
throw "Result Not Found";
}
}
function getValueWhere_descending($table_name,$value,$row_value,$value_entered)
{
$query = $this->link->query("SELECT $value from $table_name where $row_value='$value_entered' ORDER BY `id` DESC");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
function getValue_twoCoditions($table_name,$value,$row_value1,$value_entered1,$row_value2,$value_entered2)
{
try{
$query = $this->link->query("SELECT $value from $table_name where $row_value1='$value_entered1' AND $row_value2='$value_entered2'");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
catch(Exception $e)
{
throw "Result Not Found";
}
}
function getValue_twoCoditions_descending($table_name,$value,$row_value1,$value_entered1,$row_value2,$value_entered2)
{
try{
$query = $this->link->query("SELECT $value from $table_name where $row_value1='$value_entered1' AND $row_value2='$value_entered2' ORDER BY `id` DESC");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
catch(Exception $e)
{
throw "Result Not Found";
}
}
//get all the latest aricles
function getValue_latest($table_name,$value)
{
$query = $this->link->query("SELECT $value from $table_name pet ORDER BY `article_date` DESC");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
//get latest article according to the author
function getValue_latest_where($table_name,$value,$row_value,$value_entered)
{
$query = $this->link->query("SELECT $value from $table_name where $row_value='$value_entered' ORDER BY `article_date` DESC");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
//function for inserting member's details
function insertMember($name,$email_id,$dob,$gender,$contact_no,$address,$city,$postal_code,$state,$country,
$username,$password,$membership_id,$date,$expiration_date)
{
$query = $this->link->prepare("INSERT INTO `member_table`(`name`, `email_id`, `dob`, `gender`, `contact_no`,`address`, `city`, `postal_code`, `state`, `country`, `username`, `password`, `membership_id`, `date`, `expiration_date`) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)");
$values = array($name,$email_id,$dob,$gender,$contact_no,$address,$city,$postal_code,$state,$country,$username,$password,$membership_id,$date,$expiration_date);
$query->execute($values);
return $query->rowCount();
}
/*method for inserting member in mlm_info
//Auth Dipanjan
*/
function insertMembershipId($membership_id,$date){
$query = $this->link->prepare("INSERT INTO `mlm_info`(`membership_id`, `date`) VALUES (?,?)");
$values = array($membership_id,$date);
$query->execute($values);
return $query->rowCount();
}
/*method for inserting withdrawal amount
//Auth Dipanjan
*/
function insertWithdrawalAmount($membership_id,$withdraw_amount,$frozen_money,$withdraw_id,$date,$status){
$query = $this->link->prepare("INSERT INTO `withdraw_log`(`membership_id`, `withdraw_amount`, `frozen_money`, `withdraw_order_id`, `date`, `status`) VALUES (?,?,?,?,?,?)");
$values = array($membership_id,$withdraw_amount,$frozen_money,$withdraw_id,$date,$status);
$query->execute($values);
return $query->rowCount();
}
/*method for inserting information in money transfer log
//Auth Dipanjan
*/
function insertDebitAmount($membership_id,$product_id,$quantity,$date,$amount,$system_balence,$frozen_money,$notes){
$query = $this->link->prepare("INSERT INTO `money_transfer_log`
(`membership_id`, `product_id`, `product_quantity`, `date`, `debit`, `system_balence`, `frozen_money`, `notes`) VALUES (?,?,?,?,?,?,?,?)");
$values = array($membership_id,$product_id,$quantity,$date,$amount,$system_balence,$frozen_money,$notes);
$query->execute($values);
return $query->rowCount();
}
/*method for inserting information in money transfer log
//Auth Dipanjan
*/
function insertCreditAmount($membership_id,$product_id,$quantity,$date,$amount,$system_balence,$frozen_money,$notes){
$query = $this->link->prepare("INSERT INTO `money_transfer_log`
(`membership_id`, `product_id`, `product_quantity`, `date`, `credit`, `system_balence`, `frozen_money`, `notes`) VALUES (?,?,?,?,?,?,?,?)");
$values = array($membership_id,$product_id,$quantity,$date,$amount,$system_balence,$frozen_money,$notes);
$query->execute($values);
return $query->rowCount();
}
/*method for inserting information in purchase info table
//Auth Dipanjan
*/
function insertPurchaseInfo($order_id,$product_id,$quantity,$date,$payment_method,$payment_status){
$query = $this->link->prepare("INSERT INTO `purchase_info`(`order_id`, `product_id`, `quantity`, `date`, `payment_method`, `payment_status`) VALUES (?,?,?,?,?,?)");
$values = array($order_id,$product_id,$quantity,$date,$payment_method,$payment_status);
$query->execute($values);
return $query->rowCount();
}
/*method for inserting information in purchase info table
//Auth Dipanjan
*/
function insertPurchaseInfoPaypal($order_id,$product_id,$quantity,$date,$payment_method,$payment_request,$payment_status){
$query = $this->link->prepare("INSERT INTO `purchase_info`(`order_id`, `product_id`, `quantity`, `date`, `payment_method`, `payment_request`, `payment_status`) VALUES (?,?,?,?,?,?,?)");
$values = array($order_id,$product_id,$quantity,$date,$payment_method,$payment_request,$payment_status);
$query->execute($values);
return $query->rowCount();
}
/*method for inserting account information of member
//Auth Dipanjan
*/
function insertAcDetails($membership_id,$ac_name,$ac_no,$bank,$branch,$ifsc,$status){
$query = $this->link->prepare("INSERT INTO `member_account_details`(`membership_id`, `ac_name`, `ac_no`, `bank`, `branch`, `ifsc_code`, `status`) VALUES (?,?,?,?,?,?,?)");
$values = array($membership_id,$ac_name,$ac_no,$bank,$branch,$ifsc,$status);
$query->execute($values);
return $query->rowCount();
}
//getting last value of a column
function getLastValue($table_name,$column_name,$sorting_column){
$query = $this->link->query("SELECT $column_name FROM $table_name ORDER BY $sorting_column DESC LIMIT 1");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
//function for search functionality
function getvalue_search($table_name,$value,$row_value,$value_entered)
{
//$value_entered = htmlentities($value_entered);
$query = $this->link->query("SELECT $value from $table_name WHERE (( $row_value LIKE '%".$value_entered."%') OR (`company_city` LIKE '%".$value_entered."%') OR (`company_name` LIKE '%".$value_entered."%')) AND (`status` = '1') AND (`end_date` >= CURDATE()) ORDER BY RAND()");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
//get ads according to email(username)
function getValue_email($table_name,$value,$row_value,$value_entered)
{
//$value_entered = htmlentities($value_entered);
$query = $this->link->query("SELECT $value from $table_name WHERE $row_value LIKE '".$value_entered."'");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
//get submenus according to the position
function getSubmenu_ordered($table_name,$value,$order)
{
$query = $this->link->query("SELECT $value from $table_name HAVING $order > 0 ORDER BY $order ASC");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
//get vertical nav sorted by parent_id and position
function getMenu_sorted($table_name,$value,$order,$value_parent)
{
$query = $this->link->query("SELECT $value from $table_name HAVING $order = $value_parent ORDER BY $order,`parent_id`,`position` ASC");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
// function to store user tracking results
function insertTrackingValues($companyName,$browserName,$OS,$browserVersion,$date,$ip,$time){
$query = $this->link->prepare("INSERT INTO `tracking`(`browserversion`, `os`, `browsername`, `ip`, `category`, `date`, `time`) VALUES (?,?,?,?,?,?,?)");
$values = array($browserVersion,$OS,$browserName,$ip,$companyName,$date,$time);
$query->execute($values);
}
//function for update of values
function updateValue_email_owner($table_name,$column_name,$column_value,$email)
{
$query = $this->link->prepare("UPDATE `$table_name` SET `$column_name` = '$column_value' WHERE `owner_email` = '$email'");
$query->execute();
$count = $query->rowCount();
return $count;
}
//function for update of values
function updateValue_email_company($table_name,$column_name,$column_value,$email)
{
$query = $this->link->prepare("UPDATE `$table_name` SET `$column_name` = '$column_value' WHERE `company_name` = '$email'");
$query->execute();
$count = $query->rowCount();
return $count;
}
/*
- method for updating the values using where clause
- auth: Dipanjan
*/
function updateValueWhere($table_name,$update_column,$update_value,$column_name,$column_value)
{
$query = $this->link->prepare("UPDATE `$table_name` SET `$update_column`= '$update_value' WHERE `$column_name` = '$column_value'");
$query->execute();
$count = $query->rowCount();
return $count;
}
/*
- function to get the likely values of keyword
- auth: Dipanjan
*/
function getValue_likely($table_name,$value,$column_name,$keyword)
{
$query = $this->link->prepare("SELECT $value from $table_name WHERE $column_name LIKE '%$keyword%'");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
/*
- function to get the likely values of keyword with descending
- auth: Dipanjan
*/
function getValue_likely_descending($table_name,$value,$column_name,$keyword)
{
$query = $this->link->prepare("SELECT $value from $table_name WHERE $column_name LIKE '%$keyword%' ORDER BY `id` DESC");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
/*
- function to get the likely values of keyword
- auth: Dipanjan
*/
function getValue_latestDate($table_name,$value,$no)
{
$query = $this->link->prepare("SELECT $value from $table_name ORDER BY `date` DESC LIMIT $no");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
/*method for inserting values to given table
//Auth Dipanjan
*/
function insertValue($table_name,$column_name,$column_values){
//declaring variables for preparing the query
$column = "";
$value = "";
for($i=0;$i<count($column_name);$i++)
{
$column = $column."`".$column_name[$i]."`, ";
$value = $value."?,";
}
//modifying the string for column name and values
$column = substr($column,0,-2);
$value = substr($value,0,-1);
$query = $this->link->prepare("INSERT INTO `$table_name`($column) VALUES ($value)");
$query->execute($column_values);
return $query->rowCount();
}
/* ====== codes written by vasu ================== */
/* insert the new address provided by the users at the time
* of checkout
*/
function insertAddress($userShippingAddress,$dataType,$deliveryStatus,$ipaddress,$orderid){
if($dataType == 'olddata'){
$wholeAddress = $userShippingAddress;
}
else if($dataType == 'newdata'){
$wholeAddress = $userShippingAddress['f_name'].' '.$userShippingAddress['l_name'].
', <br>'.$userShippingAddress['company_name'].','.$userShippingAddress['company_id'].
', <br>'. $userShippingAddress['address_1'].'<br>'.$userShippingAddress['address_2'].
','.$userShippingAddress['city'].'<br> pin:'.$userShippingAddress['p_code'].
', <br>'. $userShippingAddress['state'].','.$userShippingAddress['country'];
// this line takes the users or guest email if they are entering the new shipping address
$email_id = $userShippingAddress['email_id'];
}
$date = date('Y-m-d');
if(!isset($email_id))
{
$email_id = "";
}
//checks whether orderId session variable exists or not
$query = $this->link->prepare("select * from `purchase_log` where order_id = '$orderid'");
$query->execute();
if($query->rowcount()!=1){
$query = $this->link->prepare("INSERT INTO `purchase_log`(`shipping_address`,`date`,`delivery_status`,`ip_address`,`email_id`,`order_id`) VALUES (?,?,?,?,?,?)");
$values = array($wholeAddress,$date,$deliveryStatus,$ipaddress,$email_id,$orderid);
$query->execute($values);
echo $orderid;
return $query->rowcount();
}
else {
$query = $this->link->prepare("UPDATE `purchase_log` SET `ip_address`='$ipaddress',`date`='$date',`delivery_status`=$deliveryStatus,`email_id`='$email_id',`shipping_address`='$wholeAddress' WHERE order_id='$orderid'");
$query->execute();
echo $orderid;
return $query->rowcount();
}
}
function insertShipCon($orderId,$shipComment){
$query = $this->link->prepare("UPDATE `purchase_log` SET `shipping_comments`='$shipComment' WHERE order_id = '$orderId'");
$query->execute();
return $query->rowcount();
}
function insertPaymentCon($orderId,$paymentMethod,$orderCom){
$query = $this->link->prepare("UPDATE `purchase_log` SET `payment_method`='$paymentMethod',`order_comments`='$orderCom' WHERE order_id = '$orderId'");
$query->execute();
echo $orderId;
return $query->rowcount();
}
function insertPayment($orderId,$totalPrice,$memberid,$allProducts){
$query = $this->link->prepare("UPDATE `purchase_log` SET `product_id`='$allProducts',`membership_id`='$memberid', `price`='$totalPrice' WHERE order_id = '$orderId'");
$query->execute();
return $query->rowcount();
}
/*
* to get the maxpick value of a particular product
*/
function getValueWhereIn($table_name,$value,$row_value,$valueList)
{
try{
$query = $this->link->prepare("SELECT $value from $table_name where $row_value IN $valueList");
$query->execute();
$rowcount = $query->rowCount();
if($rowcount > 0){
$result = $query->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
else{
return $rowcount;
}
}
catch(Exception $e)
{
throw "Result Not Found";
}
}
/*
* Insert 1 for activated user
* Auth vasu naman
*/
function activateUser($membership_id,$email){
$query = $this->link->prepare("UPDATE `member_table` SET `membership_validiation`=1 WHERE membership_id = '$membership_id'");
$query->execute();
return $query->rowCount();
}
/* ====== codes written by vasu end here ========== */
}
?>
have even check on the include still not working....
Hope you can help me

Pass table variable to SELECT function

I have a getData() function, and a database with two tables: employers and members.
I would like to pass a variable containing the table name, so inside an "if" I could execute the appropriate SELECT statement. My problem I believe that after the "if" the $stmt->bind_param(); doesn't know which $stmt to bind the take.
Any ideas on how I could achieve this?
Thanks
public function getData($table)
{
if ($table == "employers")
{
$stmt = $this->link->prepare("SELECT * FROM employers ");
}
else
{
$stmt = $this->link->prepare("SELECT * FROM members ");
}
$stmt->bind_param();
if ($stmt->execute())
{
$result = $stmt->get_result();
while($row = $result->fetch_array(MYSQLI_ASSOC))
{
$row = array_map('stripslashes', $row);
$dataArray[] = $row;
}
}
return $dataArray;
}

No, since you aren't binding anything, that ->bind_param method is superfluous. Just take that off.
public function getData($table)
{
$dataArray = array();
$t = ($table === 'employers') ? 'employers' : 'members';
$query = "SELECT * FROM $t";
$stmt = $this->link->prepare($query);
if($stmt->execute()) {
$result = $stmt->get_result();
while($row = $result->fetch_assoc()) {
$row = array_map('stripslashes', $row);
$dataArray[] = $row;
}
}
return $dataArray;
}
Sample Usage:
$data = $aministrator_query->getData('members');
$tbody = '';
foreach($data as $row) {
$tbody .= "<tr><td>{$row['user_id']}</td><td>{$row['user_password']}</td><td>{$row['user_first_name']}</td><td>{$row['user_last_name']}</td></tr>";
}
$table = sprintf('<table><thead><tr><th>ID</th><th>Password</th><th>First Name</th><th>Last Name</th></tr></thead><tbody>%s</tbody></table>', $tbody);
echo $table;

PHP prepared statement not returning array

My array is empty when I'm binding an id variable. The table contains 5 columns that I'd like in an array. This is what I tried:
$records = array();
$id = 22;
if($results = $db->prepare("SELECT * FROM categories WHERE id = ?")) {
$results->bind_param('i', $id);
$results->execute();
if($results->num_rows) {
while($row = $results->fetch_object()) {
$records[] = $row;
}
$results->free();
}
}
print_r($records);

you are binding param 'i' but using a '?' placeholder. Use one of these:
if($results = $db->query("SELECT * FROM categories WHERE id = ?")) {
$results->bind_param(1, $id);
or
if($results = $db->query("SELECT * FROM categories WHERE id = :i")) {
$results->bind_param(':i', $id);
See http://www.php.net/manual/en/pdostatement.bindparam.php for more examples.

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