Verifying MYSQL executed a result not using get_result() - php

What's the best way to verify mysql executed successfully and then returned a result when you CANNOT use the following code:
$db = dbConnect();
//begin prepared statements to search db
$stmt = $db->prepare("SELECT email,authentication,email_confirm,externalid,password,id, admin FROM users WHERE email=?");
$stmt->bind_param('s',$email);
$stmt->execute();
$result = $stmt->get_result();
if (!$result){
//error statement
} if (!(mysqli_num_rows($result)==0)){
//action to perform
} else {
// no result returned
}
I was using get_result numerous times in my scripts, and my hosting provider doesn't have mysqlnd driver so I have to rewrite a lot of code. I know I am limited to bind_result and fetch(), but I need a little help rewriting the code since my mindset is stuck in the way I first did it.
I'm also using mysqli and not PDO.

The Mysqli fetch() function will return one of 3 values:
TRUE - Success. Data has been fetched
FALSE - Error occurred
NULL - No more rows/data exists or data truncation occurred
This means you can set your query like this:
$db = dbConnect();
$query = "SELECT email,authentication,email_confirm,externalid,password,id, admin FROM users WHERE email=?";
$stmt = $db->prepare();
$stmt->bind_param('s',$email);
$stmt->execute();
$stmt->bind_result($email,$auth,$email_confirm,$externalid,$password,$id,$admin);
// Will only execute loop if returns true
$record_count = 0;
while($result = $stmt->fetch())
{
// Increment counter
$record_count++;
// Do something with bound result variables
echo("Email is $email");
}
// After the loop we either ran out of results or had an error
if($result === FALSE)
{
echo("An error occurred: " . $db->error());
}
elseif($record_count == 0)
{
echo("No records exist.");
}

Related

False positive PDO rowcount

I'm trying to test if a user has activated their account using rowcount. Currently it's returning a positive even when I deliberately edit the database data to fail.
I tested my SQL to see if that was the problem, it seemed to return the expected values. I'm assuming it is something to do with my PHP code
try
{
$db = new Database;
$query = "SELECT COUNT(*),accountStatus, email FROM users WHERE email = :email AND accountStatus ='Active'";
$stmt = $db->prepare($query);
$stmt->bindValue(':email', $email);
$stmt->execute();
$count = $stmt->rowCount();
}
catch(Exception $e)
{
$errors[] = ["name" => "email", "error" => "Something went wrong contact the administrator or try again later"];
}
if(count($count > 0))
{
return true;
}
else
{
return false;
}
From the docs:
PDOStatement::rowCount() returns the number of rows affected by the last DELETE, INSERT, or UPDATE statement executed by the corresponding PDOStatement object.
If the last SQL statement executed by the associated PDOStatement was a SELECT statement, some databases may return the number of rows returned by that statement. However, this behaviour is not guaranteed for all databases and should not be relied on for portable applications.

How to check no. of rows returned when using MYSQLI_STMT_PREPARE and MYSQLI_FETCH_ARRAY?

I thought I could use MYSQLI_STMT_NUM_ROWS and MYSQLI_STMT_STORE_RESULTto check for no. of rows returned. (see commented lines ///1///, ///2///, ///3///)
But it doesn't seem to in the context below.
This codes does work (without the commented lines), but I am trying to add an extra check, to confirm that no more than 1 record is returned. (even though this should always be the case, as the email field in the table is unique, but it doesn't hurt to do the check anyway).
Can anyone shed some light on what I'm doing wrong?
This is the error I get below (line 86 if the WHILE ... line):
An error occurred in script 'L:\includes\login_functions.inc.php' on line 86: mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given
NOTE:
This a stripped down version of the original code.
$form_email and $form_pass are originated from form input.
Code is procedural, because I like it that way.
<?php
// Prepared statement.
$prep_sel = 'SELECT user_id, first_name, user_level, pass FROM users WHERE email=? and active is null';
// Initialise connection.
$stmt_sel = mysqli_stmt_init($dbc);
// Check if there are any DB connection problems.
....
// Prepare statement, bind parameters (an integer and a string) and execute the statement
if (mysqli_stmt_prepare($stmt_sel, $prep_sel)) {
mysqli_stmt_bind_param($stmt_sel, 's', $form_email);
mysqli_stmt_execute($stmt_sel);
///1///mysqli_stmt_store_result($stmt_sel);
}
///2///if (mysqli_stmt_num_rows($stmt_sel) == 1) { // one record found.
// Get the results.
$result = mysqli_stmt_get_result($stmt_sel);
while ($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) {
// Now check if the passwords match.
if (password_verify($form_pass, $row['pass'])) {
return array(true, $row);
} else {
$errors[] = 'the details you provided does not match our records';
$errors[] = 'your account has not been activated';
}
}
///3///}
/* close statement */
mysqli_stmt_close($stmt_sel);
?>
After calling mysqli_stmt_store_result(), the MySQL driver will not permit you to operate on a result set until all rows are fetched or the result set is freed and the statement closed. So a subsequent call to mysqli_stmt_get_result() will return false, and probably result in an error like
Commands out of sync; you can't run this command now
which you may check with echo mysqli_error($dbc);
Transferring the statement's result set with mysqli_stmt_get_result() will give you access to its num_rows property, so you actually don't need to use mysqli_stmt_store_result(). Instead just rely on mysqli_stmt_get_result() before checking the number of rows returned:
if (mysqli_stmt_prepare($stmt_sel, $prep_sel)) {
mysqli_stmt_bind_param($stmt_sel, 's', $form_email);
mysqli_stmt_execute($stmt_sel);
// Transfer the result set here:
$result = mysqli_stmt_get_result($stmt_sel);
// Then check rows returned on the $result obj
// using mysqli_num_rows(), not mysqli_stmt_num_rows()
if (mysqli_num_rows($result) == 1) {
while ($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) {
// Check your password, etc....
}
}
else {
// More than 1, do whatever you need to handle this
}
// Close it
mysqli_stmt_close($stmt_sel);
}
function authenticateUser($email, $password){
$stmt = $db->prepare("SELECT user_id, first_name, user_level, pass FROM users WHERE email=? and active is null");
$stmt->bind_param('s', $email);
$stmt->execute();
$res = $stmt->get_result();
if($res->num_rows > 0){
$hash = $res->fetch_object()->pass;
if(password_verify($password, $hash)){
return true;
}
}
return false;
}
call the function
if(authenticateUser($_POST['email'], $_POST['password'])){
//do something
}
else{
echo "Invalid Email/Password";
}

Writing a Select Where statement in PHP and MySQL

Would someone please me with the code below, I am inexperienced in this area and my class in SQL was "A long time ago in a galaxy far, far away..." I know the connection string works because I have used it in other functions with this app. I have even used the code below for retrieving *rows from another table in another function, for the most part, except that I didn't use the WHERE clause.
First, I am able to store IP addresses in the table using a function and it is working well. Now I want to check to see if a given one exist in this table. Partial code is given below.
What seems to always return is 0 rows. I have put in test data into the table and hard-coded the $ipA, but I still get 0 rows return. Please help if possible and thanks for the effort spent.
function checkDB($ipA) {
require_once('connection.inc.php');
$resultAns = "";
//create db connection
$conn = dbConnect();
//init prepared stmt
$stmt = $conn->stmt_init();
//Set sql query for ipAddress search
//prepare the SQL query
$sql = 'SELECT * FROM ipAddress WHERE ipA = ?';
//submit the query and capture the result
if ($stmt->prepare($sql)) {
$stmt->bind_param('s', $ipA);
$stmt = $stmt->execute();
//if qry triggers error affeted_rows value becomes -1 &
//php treats -1 as true; so test for greater than 0
$numRows = $stmt->num_rows; //not to sure about the syntax here
}
// I want to know if the query brought back something or not, I don't what
// to know exactly what, only that it found a match or did not find a match.
// echos are for testing purposes to show me where I am landing.
if ($numRows == 0) {
echo '<script type="text/javascript">window.alert("numRows = 0")</script>';
$resultAns = 0;
} elseif ($numRows == 1) {
echo '<script type="text/javascript">window.alert("numRows = 1")</script>';
$resultAns = 1;
}
return $resultAns;
}
Try storing the result after you execute
$stmt->store_result();
Use $stmt->store_result(); before you call num_rows.
While the others caught one reason that $numRows would never receive a value other than 0, the other piece of code that was flawed and caused problems was...
$stmt = $stmt->execute(); which should have been just $stmt->execute();
I must have mixed it up with other code I wrote from somewhere else.
Thanks for the answers, they did help.

MySQLI Prepared Statement: num_rows & fetch_assoc

Below is some poorly written and heavily misunderstood PHP code with no error checking. To be honest, I'm struggling a little getting my head around the maze of PHP->MySQLi functions! Could someone please provide an example of how one would use prepared statements to collect results in an associative array whilst also getting a row count from $stmt? The code below is what I'm playing around with. I think the bit that's throwing me off is using $stmt values after store_result and then trying to collect an assoc array, and I'm not too sure why...
$mysqli = mysqli_connect($config['host'], $config['user'], $config['pass'], $config['db']);
$stmt = $mysqli->prepare("SELECT * FROM licences WHERE generated = ?");
$stmt->bind_param('i', $core['id']);
$result = $stmt->execute();
$stmt->store_result();
if ($stmt->num_rows >= "1") {
while($data = $result->fetch_assoc()){
//Loop through results here $data[]
}
}else{
echo "0 records found";
}
I feel a little cheeky just asking for code, but its a working demonstration of my circumstances that I feel I need to finally understand what's actually going on. Thanks a million!
I searched for a long time but never found documentation needed to respond correctly, but I did my research.
$stmt->get_result() replace $stmt->store_result() for this purpose.
So, If we see
$stmt_result = $stmt->get_result();
var_dump($stmt_result);
we get
object(mysqli_result)[3]
public 'current_field' => int 0
public 'field_count' => int 10
public 'lengths' => null
public 'num_rows' => int 8 #That we need!
public 'type' => int 0
Therefore I propose the following generic solution. (I include the bug report I use)
#Prepare stmt or reports errors
($stmt = $mysqli->prepare($query)) or trigger_error($mysqli->error, E_USER_ERROR);
#Execute stmt or reports errors
$stmt->execute() or trigger_error($stmt->error, E_USER_ERROR);
#Save data or reports errors
($stmt_result = $stmt->get_result()) or trigger_error($stmt->error, E_USER_ERROR);
#Check if are rows in query
if ($stmt_result->num_rows>0) {
# Save in $row_data[] all columns of query
while($row_data = $stmt_result->fetch_assoc()) {
# Action to do
echo $row_data['my_db_column_name_or_ALIAS'];
}
} else {
# No data actions
echo 'No data here :(';
}
$stmt->close();
$result = $stmt->execute(); /* function returns a bool value */
reference : http://php.net/manual/en/mysqli-stmt.execute.php
so its just sufficient to write $stmt->execute(); for the query execution.
The basic idea is to follow the following sequence :
1. make a connection. (now while using sqli or PDO method you make connection and connect with database in a single step)
2. prepare the query template
3. bind the the parameters with the variable
4. (set the values for the variable if not set or if you wish to change the values) and then Execute your query.
5. Now fetch your data and do your work.
6. Close the connection.
/*STEP 1*/
$mysqli = mysqli_connect($servername,$usrname,$pswd,$dbname);
/*STEP 2*/
$stmt = $mysqli->prepare("SELECT * FROM licences WHERE generated = ?");
/*Prepares the SQL query, and returns a statement handle to be used for further operations on the statement.*/
//mysqli_prepare() returns a statement object(of class mysqli_stmt) or FALSE if an error occurred.
/* STEP 3*/
$stmt->bind_param('i', $core['id']);//Binds variables to a prepared statement as parameters
/* STEP 4*/
$result = $stmt->execute();//Executes a prepared Query
/* IF you wish to count the no. of rows only then you will require the following 2 lines */
$stmt->store_result();//Transfers a result set from a prepared statement
$count=$stmt->num_rows;
/*STEP 5*/
//The best way is to bind result, its easy and sleek
while($data = $stmt->fetch()) //use fetch() fetch_assoc() is not a member of mysqli_stmt class
{ //DO what you wish
//$data is an array, one can access the contents like $data['attributeName']
}
One must call mysqli_stmt_store_result() for (SELECT, SHOW, DESCRIBE, EXPLAIN), if one wants to buffer the complete result set by the client, so that the subsequent mysqli_stmt_fetch() call returns buffered data.
It is unnecessary to call mysqli_stmt_store_result() for other queries, but if you do, it will not harm or cause any notable performance in all cases.
--reference: php.net/manual/en/mysqli-stmt.store-result.php
and http://www.w3schools.com/php/php_mysql_prepared_statements.asp
One must look up the above reference who are facing issue regarding this,
My answer may not be perfect, people are welcome to improve my answer...
If you would like to collect mysqli results into an associative array in PHP you can use fetch_all() method. Of course before you try to fetch the rows, you need to get the result with get_result(). execute() does not return any useful values.
For example:
<?php
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli($config['host'], $config['user'], $config['pass'], $config['db']);
$mysqli->set_charset('utf8mb4'); // Don't forget to set the charset!
$stmt = $mysqli->prepare("SELECT * FROM licences WHERE generated = ?");
$stmt->bind_param('i', $core['id']);
$stmt->execute(); // This doesn't return any useful value
$result = $stmt->get_result();
$data = $result->fetch_all(MYSQLI_ASSOC);
if ($data) {
foreach ($data as $row) {
//Loop through results here
}
} else {
echo "0 records found";
}
I am not sure why would you need num_rows, you can always use the array itself to check if there are any rows. An empty array is false-ish in PHP.
Your problem here is that to do a fetch->assoc(), you need to get first a result set from a prepared statement using:
http://php.net/manual/en/mysqli-stmt.get-result.php
And guess what: this function only works if you are using MySQL native driver, or "mysqlnd". If you are not using it, you'll get the "Fatal error" message.
You can try this using the mysqli_stmt function get_result() which you can use to fetch an associated array. Note get_result returns an object of type mysqli_result.
$stmt->execute();
$result = $stmt->get_result(); //$result is of type mysqli_result
$num_rows = $result->num_rows; //count number of rows in the result
// the '=' in the if statement is intentional, it will return true on success or false if it fails.
if ($result_array = $result->fetch_assoc(MYSQLI_ASSOC)) {
//loop through the result_array fetching rows.
// $ rows is an array populated with all the rows with an associative array with column names as the key
for($j=0;$j<$num_rows;$j++)
$rows[$j]=$result->fetch_row();
var_dump($rows);
}
else{
echo 'Failed to retrieve rows';
}

PHP Commands Out of Sync error

I am using two prepared statements in PHP/MySQLi to retrieve data from a mysql database. However, when I run the statements, I get the "Commands out of sync, you can't run the command now" error.
Here is my code:
$stmt = $mysqli->prepare("SELECT id, username, password, firstname, lastname, salt FROM members WHERE email = ? LIMIT 1";
$stmt->bind_param('s', $loweredEmail);
$stmt->execute();
$stmt->store_result();
$stmt->bind_result($user_id, $username, $db_password, $firstname, $lastname, $salt);
$stmt->fetch();
$stmt->free_result();
$stmt->close();
while($mysqli->more_results()){
$mysqli->next_result();
}
$stmt1 = $mysqli->prepare("SELECT privileges FROM delegations WHERE id = ? LIMIT 1");
//This is where the error is generated
$stmt1->bind_param('s', $user_id);
$stmt1->execute();
$stmt1->store_result();
$stmt1->bind_result($privileges);
$stmt1->fetch();
What I've tried:
Moving the prepared statements to two separate objects.
Using the code:
while($mysqli->more_results()){
$mysqli->next_result();
}
//To make sure that no stray result data is left in buffer between the first
//and second statements
Using free_result() and mysqli_stmt->close()
PS: The 'Out of Sync' error comes from the second statement's '$stmt1->error'
In mysqli::query If you use MYSQLI_USE_RESULT all subsequent calls will return error Commands out of sync unless you call mysqli_free_result()
When calling multiple stored procedures, you can run into the following error: "Commands out of sync; you can't run this command now".
This can happen even when using the close() function on the result object between calls.
To fix the problem, remember to call the next_result() function on the mysqli object after each stored procedure call. See example below:
<?php
// New Connection
$db = new mysqli('localhost','user','pass','database');
// Check for errors
if(mysqli_connect_errno()){
echo mysqli_connect_error();
}
// 1st Query
$result = $db->query("call getUsers()");
if($result){
// Cycle through results
while ($row = $result->fetch_object()){
$user_arr[] = $row;
}
// Free result set
$result->close();
$db->next_result();
}
// 2nd Query
$result = $db->query("call getGroups()");
if($result){
// Cycle through results
while ($row = $result->fetch_object()){
$group_arr[] = $row;
}
// Free result set
$result->close();
$db->next_result();
}
else echo($db->error);
// Close connection
$db->close();
?>
I hope this will help
"Commands out of sync; you can't run this command now"
Details about this error can be found in the mysql docs. Reading those details makes it clear that the result sets of a prepared statement execution need to be fetched completely before executing another prepared statement on the same connection.
Fixing the issue can be accomplished by using the store result call. Here is an example of what I initially was trying to do:
<?php
$db_connection = new mysqli('127.0.0.1', 'user', '', 'test');
$post_stmt = $db_connection->prepare("select id, title from post where id = 1000");
$comment_stmt = $db_connection->prepare("select user_id from comment where post_id = ?");
if ($post_stmt->execute())
{
$post_stmt->bind_result($post_id, $post_title);
if ($post_stmt->fetch())
{
$comments = array();
$comment_stmt->bind_param('i', $post_id);
if ($comment_stmt->execute())
{
$comment_stmt->bind_result($user_id);
while ($comment_stmt->fetch())
{
array_push($comments, array('user_id' => $user_id));
}
}
else
{
printf("Comment statement error: %s\n", $comment_stmt->error);
}
}
}
else
{
printf("Post statement error: %s\n", $post_stmt->error);
}
$post_stmt->close();
$comment_stmt->close();
$db_connection->close();
printf("ID: %d -> %s\n", $post_id, $post_title);
print_r($comments);
?>
The above will result in the following error:
Comment statement error: Commands out of sync; you can't run this command now
PHP Notice: Undefined variable: post_title in error.php on line 41
ID: 9033 ->
Array
(
)
Here is what needs to be done to make it work correctly:
<?php
$db_connection = new mysqli('127.0.0.1', 'user', '', 'test');
$post_stmt = $db_connection->prepare("select id, title from post where id = 1000");
$comment_stmt = $db_connection->prepare("select user_id from comment where post_id = ?");
if ($post_stmt->execute())
{
$post_stmt->store_result();
$post_stmt->bind_result($post_id, $post_title);
if ($post_stmt->fetch())
{
$comments = array();
$comment_stmt->bind_param('i', $post_id);
if ($comment_stmt->execute())
{
$comment_stmt->bind_result($user_id);
while ($comment_stmt->fetch())
{
array_push($comments, array('user_id' => $user_id));
}
}
else
{
printf("Comment statement error: %s\n", $comment_stmt->error);
}
}
$post_stmt->free_result();
}
else
{
printf("Post statement error: %s\n", $post_stmt->error);
}
$post_stmt->close();
$comment_stmt->close();
$db_connection->close();
printf("ID: %d -> %s\n", $post_id, $post_title);
print_r($comments);
?>
A couple things to note about the above example:
The bind and fetch on the statement still works correctly.
Make sure the results are freed when the processing is done.
For those of you who do the right thing and use stored procedures with prepared statements.
For some reason mysqli cannot free the resources when using an output variable as a parameter in the stored proc. To fix this simply return a recordset within the body of the procedure instead of storing the value in an output variable/parameter.
For example, instead of having SET outputVar = LAST_INSERT_ID(); you can have SELECT LAST_INSERT_ID(); Then in PHP I get the returned value like this:
$query= "CALL mysp_Insert_SomeData(?,?)";
$stmt = $mysqli->prepare($query);
$stmt->bind_param("is", $input_param_1, $input_param_2);
$stmt->execute() or trigger_error($mysqli->error); // trigger_error here is just for troubleshooting, remove when productionizing the code
$stmt->store_result();
$stmt->bind_result($output_value);
$stmt->fetch();
$stmt->free_result();
$stmt->close();
$mysqli->next_result();
echo $output_value;
Now you are ready to execute a second stored procedure without having the "Commands out of sync, you can't run the command now" error. If you were returning more than one value in the record set you can loop through and fetch all of them like this:
while ($stmt->fetch()) {
echo $output_value;
}
If you are returning more than one record set from the stored proc (you have multiple selects), then make sure to go through all of those record sets by using $stmt->next_result();

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