I'm trying to implement pagination using PHP. I found that calling exec to the connected database prevents the further query calls from working.
The piece of code at hand:
<?php
// Pagination logic
//Here we count the number of results
$query = "SELECT COUNT(*) as num FROM gig";
$total_pages = $db->exec($query);
$total_pages = $total_pages[num];
?>
After it if I try to use a query such as:
<?php>
foreach ($db->query("SELECT sname, start, venue FROM gig WHERE start = '0000-00-00 00:00:00'") as $a) {
$row="<tr><td>$a[sname]</td><td>To be announced</td><td>$a[venue]</td></tr>\n";
print $row;
}
?>
it returns
Warning: Invalid argument supplied for foreach()
As soon as the first code block is removed, the query works fine. When I check the value of $total_pages, it's 0, so something must be going wrong along the way. As far as I know, I use it in the same way as the query(which works on its own), so is there any reason why it doesn't work?
The PDO is initialized in the following way:
try {
$db = new PDO("mysql:dbname=$db_name;host=$db_server", $db_user, $db_pw);
} catch (PDOException $e) {
die('Connection failed: ' . $e->getMessage());
}
session_start();
From Manual
PDO::exec() does not return results from a SELECT statement. For a
SELECT statement that you only need to issue once during your program,
consider issuing PDO::query(). For a statement that you need to issue
multiple times, prepare a PDOStatement object with PDO::prepare() and
issue the statement with PDOStatement::execute().
Used a function of the STATEMENT object had after using querying to count the rows instead of exec:
$dbq = $db->query("SELECT * FROM gig");
$rows = $dbq->rowCount();
About the latter code block not working because of the exec failing - it seems to just be the way php queries work, if one fails, all fail. The foreach() error is for the object it's provided is not an array, for it failed.
Related
I am iterating rows of a csv file.
On row 1, I call stored procedure (import_extended_data_sp) and it succeeds.
On row 2, the call fails with :
Strict Standards mysqli::next_result(): There is no next result set.
However, with the call being exactly the same as the first, I am struggling to see why ?
I have now hard coded test values as parameters, and checked that the Sproc has no issue with the same values being given twice.
It still fails on the second call !?
Am wondering if there is some nuance of mysqli, where I need to clear or reset something before making the second call ?
<?php include("cnn.php");?>
<?php include("fn_db.php");?>
# ... get csv file (skipped for brevity) #
while($row = fgetcsv($file_data))
{
$line = array_combine($head, $row);
# This call works on every loop - no issues
$id = placemark_to_db($mysqli,$v_header,$line['id_placemark'],$line['name'],$line['swim_type'],$line['latitude'],$line['longitude'],$line['description']);
# This next line only succeeds on first call, but fails on next while loop
$x = xtended_to_db($mysqli,'99','[{"xtra":"oo"}]');
}
** fn_db.php >> xtended_to_db**
function xtended_to_db($cn,$id,$jsonarray){
# procedure returns a rowcount in output parameter
$cn->multi_query( "CALL import_extended_data_sp($id,'$jsonarray',#out);select #out as _out");
$cn->next_result();
$rs=$cn->store_result();
$ret = $rs->fetch_object()->_out;
$rs->free();
return $ret;
}
cnn.php
<?php
$mysqli = new mysqli("xxx.xxx.xxx.xxx","mydb","pass","user");
// Check connection
if ($mysqli -> connect_errno) {
echo "Failed to connect to MySQL: " . $mysqli -> connect_error;
exit();
}
?>
The best way to fix this error is to avoid multi_query() altogether. While it might sound like a reasonable use case with stored procedures, the truth is this function is mostly useless and very dangerous. You can achieve the same result using the normal way with prepared statements.
function xtended_to_db(mysqli $cn, $id, $jsonarray) {
$stmt = $cn->prepare('CALL import_extended_data_sp(?,?,#out)');
$stmt->bind_param('ss', $id, $jsonarray);
$stmt->execute();
$stmt = $cn->prepare('select #out as _out');
$stmt->execute();
$rs = $stmt->get_result();
return $rs->fetch_object()->_out;
}
If you are stuborn and you want to keep on using multi_query() then you need to be more careful with how you fetch results. This function is extremely difficult to get right. I am not going to show you how to fix multi_query() as I consider it too dangerous with variable input.
One last note, you really should think about getting rid of stored procedures. They are cumbersome and offer pretty much no benefit. There definitely is a better way to achieve what you want rather than calling stored procedure from PHP, but without seeing its contents I can't give you better advice.
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';
}
I have something like the following, in a function that deletes both the files and db entries:
$adapter = $this->getAdapter();
$query = $adapter->query("call find_results_by_job_id(?)", array($jobId));
$items = array();
while (($current = $query->current()) !== false)
{
$id = $current['id'];
$items[] = $id;
$query->next();
}
$this->deleteFromDataStore($items);
$result = $adapter->query("call delete_results_by_job_id(?)", array($jobId), \Zend\Db\Adapter\Adapter::QUERY_MODE_EXECUTE);
(Some of that might not look like the best way to do it, because I simplified it for this example)
I'm getting this error on the last line: SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active.
I'm assuming that the problem is because the query/adapter hasn't closed the connection from iterating results yet when I try to execute another statement. If that is the case, how can reuse the adapter, or close the query, or whatever I have to do before the last line?
The strange part is that code following almost exactly this same pattern works in another method.
Answer:
When using the PDO driver, $query->getDataSource()->getResource()->closeCursor(); fixes it
Seems like you are using an unbuffered query in MySQL.
If it is so, you will either have to turn buffering on or break execution of previous query which seems to hang?
Something like $query->close()
EDIT:
If $query is instance of StatementInterface, then there is getResource() which returns mysqli_stmt and you can call close() on it.
EDIT2: (to incorporate final resolution)
In case it uses PDO, you can get PDOStatement and call closeCursor()
Assuming you have the result of a query in your hands and you dont know whether it is a ResultSet or a Result, the following will do the job.
Tested as of Zend Framework 3.
use Zend\Db\ResultSet\ResultSet;
...
public function closeResult( $result )
{
if( is_a($result, ResultSet::class) )
{
$stmt = $result->getDataSource()->getResource();
}
else
{
$stmt = $result->getResource();
}
$stmt->closeCursor();
}
$this->adapter
->query($sql)
->execute()
->getResource()
->fetchAll(\PDO::FETCH_ASSOC);
Going through a PHP MySQL tutorial and switching the PHP out for PDO; at any rate, my query is coming up blank.
$get_cat = $that->dbh->query("SELECT `cat_name`, `cat_desc` FROM `categories`");
if(isset($get_cat))
{
while($row = $get_cat->fetch(PDO::FETCH_ASSOC))
{
printf("
<tr>
<td>".$row['cat_name']." : ".$row['cat_desc']."</td>
</tr>
");
}
}
else
{
echo '<tr><td>return is false</td></tr>';
}
$That refers to:
include('db.php');
$that = new lib();
OLD:
So, why is my query blank? Before putting the die in it would return Boolean and give in an error in the loop with the die in it just comes up blank. The categories table has data in it and the page is refreshed on submission for new entries.
NEW:
Fatal error: Call to a member function fetch() on a non-object in C:\wamp\www\forum\create_category.php on line 36
Line 36 is the while loop line.
mysql_fetch_array is not PDO. You would need something like:
while($row = $get_cat->fetch(PDO::FETCH_ASSOC))
To get your rows.
Nor can you use mysql_error() to get the error. You could use for example $that->dbh->errorInfo() but you should look into exceptions for a more robust way to catch all errors.
Edit: You should check what the error is. Using isset is pointless as you have just assigned a value to it, so it will always be set.
You need to tell PDO to throw errors.
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$res = $that->dbh->query("SELECT cat_name, cat_desc FROM categories");
while($row = $res->fetch())
{
echo "<tr><td>$row[cat_name] : $row[cat_desc]</td></tr>\n";
}
run your code, read the error message and take appropriate action
Don't forget to add the first line into your db.php file, to make the setting permanent
Your query is incorrect -- is this what you're trying to do?
SELECT `categories`.`cat_name`, `categories`.`cat_desc` FROM `categories`
Hard to know without seeing you table structure.
I am using the mysqli functions (mysqli_connect, mysqli_select_db, mysqli_query) to call 1 select query and 2 stored procedures.
It seems that when I am using the same $connection (returned by mysqli_connect) multiple times, I am getting the following error message: "Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in..."
Below is my code:
<?php
$server="localhost";
$user="user";
$pass="pass";
$db="db";
$connection=mysqli_connect("$server","$user","$pass");
mysqli_select_db($connection, "$db") or die('Unable to select database.');
//First SELECT using $connection
$query=mysqli_query($connection, "SELECT item_name FROM items ORDER BY item_name DESC");
While ($result=mysqli_fetch_array($query,MYSQL_NUM))
{
$complete_result[] = $result[0];
$total_rows = $total_rows + 1;
}
//CALL to first sp using $connection
$query2 = mysqli_query($connection, "CALL sp_check_edits_remaining()");
while ($row2 = mysqli_fetch_array($query2, MYSQL_ASSOC)) {
$edits_remaining = $row2['edits_remaining'];
} // End while
//CALL to second sp using $connection
$query3 = mysqli_query($connection, "CALL sp_edit_data");
while ($row3 = mysqli_fetch_array($query3, MYSQL_ASSOC)) {);
$edits_id = $row3['id'];
} // End while
?>
Like I described, when I call the second sp, the above code gives me the error message mentioned above. (Please note that the connection is never closed.)
However, when I create another connection and provide it to the second sp call, this error disappears. This is shown in the code below
$connection2=mysqli_connect("$server","$user","$pass");
mysqli_select_db($connection2, "$db") or die('Unable to select database.');
//CALL to second sp using $connection
$query3 = mysqli_query($connection2, "CALL sp_edit_data");
while ($row3 = mysqli_fetch_array($query3, MYSQL_ASSOC)) {
$edits_id = $row3['id'];
} // End while
Can anyone please help me why this unexpected behavior?
Thanks and in advance!
It seems I have found a solution, which might be specific to my scenario.
My stored procs return only one row in the resultset.
So, after the CALL to the first sp and the corresponding while loop, I have simply added:
mysqli_next_result($connection);
This has removed the error message/warning I was receiving.
Anyone wants to comment whether this is the 'professional' approach?
You have an error somewhere, causing one of the mysql functions (probably the query call(s)) to return a boolean false, which you then blindly use in a fetch call. You need to add extra error handling, e.g.
$query = mysqli_query($connection, "...") or die(mysqli_error($connection));
never assume a query has succeeded.
enter code hereafter the query is finished, you must close the $connection then for another query, connect and assign the $connection again.
mysqli_close($connection);
$connection=mysqli_connect(bla,bla,bla,bla).