I have this code, mainly it is meant to create shorurls for my site. But I simply cannot get it to work. Do you see something wrong with it? Is it ok to run a while() inside another one?
$urloriginal = $nt['fecha']."/".$nt['titulolower'];
mysql_query("SET NAMES 'utf8'");
$shortcheck = mysql_query("SELECT * FROM shorturls WHERE urloriginal = '".$urloriginal."' LIMIT 1");
while($urlitem = mysql_fetch_array($shortcheck)) {
if($urlitem['urloriginal'] != "0") {
echo "http://neutronico.com/u/".$urlitem['id'];
} else {
mysql_close($shortcheck);
mysql_query("INSERT into shorturls (urloriginal) VALUES ('$urloriginal')")
or die(mysql_error());
$shortget = mysql_query("SELECT * FROM shorturls WHERE urloriginal = '".$urloriginal."' LIMIT 1");
while($urlitem2 = mysql_fetch_array($shortget)) {
echo "http://neutronico.com/u/".$urlitem['id'];
};
mysql_close($shortget);
};
};
Thank you very much.
The first problem I see is that you're calling mysql_close() mid-script on a result set. Remove the call:
mysql_close($shortcheck);
mysql_close() is intended to be called on a resource link -- the database connection. Not on a query result resource. It is called implicitly when the script exits, so you needn't call it at all unless you have specific memory requirements. I think you are intending to call mysql_free_result(), but again this is called implicitly and you needn't call it unless you need to manage memory.
Later, remove this call, as it is not closing a MySQL resource link.
mysql_close($shortget);
Yes, it's OK to nest while statements.
The main problem that I didn't spot at first is that you're closing your connection in the middle of the query, thus remove all mysql_close statements.
However, after you solve this, you'll face another problem, since you're using only one MySQL connection, the second query loses all results of the first query, so probably you stop at the first row, or the first time the else branch gets executed.
To make it work, you' can choose one of the two options:
use two MySQL connections, and specify which one to use with the $link_identifier parameter mysql_query ( string $query [, resource $link_identifier ] )
run the first query, save all results in an array and then run the other queries, so the queries don't overlap. Use this option only if your table isn't too big.
Michael also suggested to check that your $urloriginal has been sanitized with mysql_real_escape_string(), or you face a risk of SQL injection.
Related
For the sake of avoiding unnecessary information, roughly my code flows as follows:
$db = new PDO(DSN, DB_USER, DB_PW);
$sql1 = "SELECT * FROM Table1";
// fetching the first result
$stt1 = $db->prepare($sql1);
if ($stt1->execute()) {
$result = $stt1->fetch(PDO::FETCH_ASSOC);
}
// doing update in the middle by using the SAME $db object, but different statement variable
$sql2 = "UPDATE Table1 SET field1 = 'footest1' WHERE id = 1";
$stt2 = $db->prepare($sql2);
$stt2->execute();
// fetching the next result
$result = $stt1->fetch(PDO::FETCH_ASSOC);
Ok, I ran this, and to my surprise, when I am fetching my next result, I get false. Does preparing another statement ($stt2) in the middle interrupt my already created $stt1?
And I have 15+ records on that table.
Update: It seems like the execute method of the statement object is the reason my second fetch is returning false. For this to work, calling $stt1->execute() again before fetching the second time solves this problem... But this shows that there is some connection via the execute method between all the statement object?
Different databases have different constraints. This is not an issue with PHP or PDO, but with the database connection.
While you can rely on any DB connector to support at least one cursor with pending rows, many databases will limit you at one, and require you to either fully fetch or explicitly close the underlying cursor before executing a new statement.
This is indeed a property of the database connection, as all PDO statements are bound to one. (Where would they fetch the data from if they didn't remain bound to the database connection?) If you're using a database that only supports one open prepared statement at a time, you'll have no choice but to either serialize your accesses or open multiple connections to the database. You might also want to take a look at the closeCursor method of the PDOStatement class.
I have checked everywhere thoroughly, and have gone through everything possible to find an answer to this. Besides saying "the code doesn't work" which obviously is not enough, I have yet to find anything that will even come close to this. I'm probably going to get downvotes, but let's see how this goes.
I am learning how to do prepared statements for a search query from the user end, and I have to do it for multiple queries. I have to bind parameters to these multiple queries, and then execute them and use them and receive multiple rows. This is most of my code, and what I currently have is not reporting any errors whatsoever. It just returns a blank white page.
I am doing this from a simple test.php file, and those are the results I'm getting.
Now for the code.
$prep1 = $test->prepare("SELECT * FROM sb__bans WHERE sb__bans.authid=? ORDER BY sb__bans.bid DESC");
$prep2 = $test->prepare("SELECT * FROM sb__bans AS bans INNER JOIN sb__admins AS admins ON bans.aid = admins.aid WHERE bans.authid=? ORDER BY bans.bid DESC");
$prep3 = $test->prepare("SELECT * FROM sb__bans AS bans INNER JOIN sb__servers AS servers ON bans.sid = servers.sid WHERE bans.authid=? ORDER BY bans.bid DESC");
$search = "steam";
$prep1->bind_param("s", $search);
$prep2->bind_param("s", $search);
$prep3->bind_param("s", $search);
$prep1->execute();
$prep2->execute();
$prep3->execute();
while($row = $prep1->fetch() && $admin = $prep2->fetch() && $sv = $prep3->fetch()) {
echo $row['test'];
echo $admin['test'];
echo $sv['test'];
}
The database is initialized above this as $test = new mysqli("localhost", "test", "test", "test");
$search = "steam" steam would be replaced with the the post variable of course, but for testing reasons I've removed that for now and am testing with just a simple variable.
What seems to be the problem here?
Thanks in advance.
Regarding the general question you asked.
There is not a single problem with having multiple queries prepared. While speaking of getting results from a prepared query, there is indeed a problem caused by the result buffering. In order to be able to execute another query, you have to call store_result()/get_result() right after execute.
Regarding the particular problem you have.
To get errors you have to ask PHP for them.
There is absolutely no point in making three queries, you have to make just one. If you have a trouble making one, ask another question marking it with mysql tag and bringing your 3 queries along.
Even for multiple queries it's just wrong idea to do multiple fetches in a single loop. Fetch your query results one by one.
Your mysqli syntax even for a single query is incomplete. You need to re-read your tutorial and practice on a single query first.
Two points:
Based on personal experience, you can only have one prepared statement in existence at a time. I suspect this is because the db requires each PS to have a session-unique name, and the PHP layer is passing some common default name rather than generating a unique name for each PS. By comparison, the PostgreSQL driver allows an optional name for each PS, but still allows only one unnamed PS to exist. Essentially this means that you must prepare, bind, execute and fetch one PS completely before you can prepare the next PS.
You're misusing mysqli_stmt::fetch(). fetch() returns only true or false, and is used to update variables which have previously been bound with mysqli_stmt::bind_result(). To retrieve values into a $row array, you must first call mysqli_stmt::get_result() to return a mysqli_result, and then call mysqli_result::fetch_array().
I new there are lots of answer as well as accepted answers related to this question but none of them solve my problem. Still I am getting this error.
Procedures:
CREATE PROCEDURE getAllProducts()
BEGIN
SELECT * FROM products;
END //
CREATE PROCEDURE getAllCategories()
BEGIN
SELECT * FROM category;
END //
Connection & calling:
$link = mysql_connect($host,$username,$password) or die(mysql_error());
mysql_select_db($database, $link) or die(mysql_error());
$allProducts = mysql_query("CALL getAllProducts");
while($row = mysql_fetch_array($allProducts)) { }
$allCategory = mysql_query("CALL getAllCategories");
while($row = mysql_fetch_array($allCategory)) { }
I've even called mysql_free_result($allProducts) before executing the next query. But nothing happens.
mysql_get_client_info() return mysqlnd 5.0.5-dev - 081106 - $Revision: 1.3.2.27 $
I found that the problem only arises if I run two queries.
As the MySQL-Documentation for 'Commands out of sync' points out:
[...] It can also happen if you try to execute two queries that return data
without calling mysql_use_result() or mysql_store_result() in between.
The Documentation for mysql_use_result() says e.g.:
After invoking mysql_query() or mysql_real_query(), you must call
mysql_store_result() or mysql_use_result() for every statement that
successfully produces a result set (SELECT, SHOW, DESCRIBE, EXPLAIN,
CHECK TABLE, and so forth). You must also call mysql_free_result()
after you are done with the result set.
Basically you need to tell your client what it should do with the result.
Well, usually this error occurs because there are still results pending from the query. There are mysqli_store_result and mysqli_free_result functions available. Since you are using mysql and mysql extension does not have such functions, you can try closing the connection after executing the first procedure and establishing the connection again to execute next procedure. Though this is not the perfect solution, but it will work in your case.
mysql_close($connection);
$connection = mysql_connect("localhost","username","password");
You can also try
mysql_free_result($allProducts);
Stored procedures always return an extra result set with errors/warnings information. As such, your stored procedures return multiple result sets (the actual result set from your select query and the extra errors/warnings result set). Calling mysql_fetch_array in a loop you only saturate one of them, leaving the other still pending, causing the error you see.
I don't know how to fix it with vanilla mysql_ library, with mysqli_ you can issue mysqli_multi_query, and then only use the first result set. See the example in the docs.
It's not a fix per se, but if you insist on staying with mysql_* functions, and assuming that you actually want to work with more complicated stored procedures (i.e. that the ones you supplied are just a simplified example) - you can change the stored procedures code to write the resultset into a temporary table (e.g. tmp_getAllProducts) instead of returning it, and then SELECT from it in your PHP.
This is what worked for me a while back when I was stuck with mysql_* and couldn't upgrade...
This is a known limitation of the mysql extension. You must either not use more than one stored procedure per connection or upgrade to mysqli.
https://bugs.php.net/bug.php?id=39727
Let's say I have something like this:
$db=new PDO($dsn);
$statement=$db->query('Select * from foo');
while ($result=$statement->fetch())
{
//do something with $result
}
How would I put another query inside of that while loop? Even if I make a new PDOStatement object, it seems that that overwrites the cursor for the topmost PDO statement. The only other solution I see is to either a) fetch the entire outer loop at once or b) open 2 different connections to the database. Neither of these seem like a good idea, are there any other solutions?
You should be able to do any other query you want inside your while loop, I'd say ; something like this :
$db=new PDO($dsn);
$statement=$db->query('Select * from foo');
while ($result=$statement->fetch())
{
$statement2 = $db->query('Select * from bar');
while ($result2=$statement2->fetch()) {
// use result2
}
}
Did you try that ? It should work...
Still, if you can (if it's OK with your data, I mean), using a JOIN to do only one query might be better for performances : 1 query instead of several is generally faster.
Sounds like what you are trying to accomplish is getting related data for the record you're looking at, why not just JOIN them in at the first query? The database will be better at connecting the dots internally than any amount of code can do externally.
But to answer your question, I don't see the harm in opening another connection to the same DSN, most likely thing to happen is that you get another instance of the PDO object pointing to the same actual connection. Also, but depending on the amount of data you're expecting you could just fetchAll and loop over a php array.
Given the following code:
// Connect to MySQL up here
$example_query = $database->prepare('SELECT * FROM table2');
if ($example_query === false) die('prepare failed');
$query = $database->prepare('SELECT * FROM table1');
$query->execute();
while ($results = $query->fetch())
{
$example_query = $database->prepare('SELECT * FROM table2');
if ($example_query === false) die('prepare failed'); //it will die here
}
I obviously attempt to prepare statements to SELET everything from table2 twice. The second one (the one in the WHILE loop) always fails and causes an error.
This is only on my production server, developing locally I have no issues so it must be some kind of setting somewhere.
My immediate thought is that MySQL has some kind of max_connections setting that is set to 1 and a connection is kept open until the WHILE loop is completed so when I try to prepare a new query it says "nope too many connected already" and shits out.
Any ideas?
EDIT: Yes I know there's no need to do it twice, in my actual code it only gets prepared in the WHILE loop, but like I said that fails on my production server so after some testing I discovered that a simple SELECT * query fails in the WHILE loop but not out of it. The example code I gave is obviously very watered down to just illustrate the issue.
Problem was that I couldn't do something while an unbuffered query was running (which it was in the WHILE loop)
Solution was to add the following line to ensure buffered queries were being used:
$database->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY,true);
There shouldn't be a need to prepare $example_query more than once. Simply execute the query inside your loop.
EDIT: If you must prepare a new query in each loop iteration, an explicit $example_query->closeCursor() at the end of the loop should free any resources associated with the statement object.