I'm using PHP ODBC library to connect to a MSSQL 2008 server (http://php.net/manual/en/ref.uodbc.php).
Some of my stored procedures do not return record sets (e.g. they just do an insert or update). I would like to be able to handle output gracefully in this situation. After the database call is made, the output is injected into an array which is returned to the application for processing. Here are the key parts of the code (excluding error handling etc):
$sql_result = odbc_exec($connection, $sql);
while ($row = odbc_fetch_array($sql_result)) {
$resultArray[$i] = $row;
$i++;
}
If $sql_result has executed successfully, but does not contain a record set (as it would following an insert or update) then odbc_fetch_array triggers this warning:
Warning: odbc_fetch_row(): No tuples available at this result index
Ideally, I'd like to test $sql_result first to see if it contains an empty record set, but every obvious attempt I've tried always leads to the same warning message.
Anyone got a neat way of checking to see if $sql_result is empty?
I don't think there is a simple way using the PHP odbc API. Usually you would use different functions to process statements that return values such as SELECT vs those like UPDATE that do not.
If this is a utility that runs arbitrary statements you could parse the statement.
This isn't an empty result set, it's no result set at all, you might be able to tell the difference by examining the result in a debugger or using var_dump.
Related
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
I know this question has been asked many times, but I've read the answers to many of the questions and still cannot understand why I am receiving this error:
Fatal error: Uncaught exception 'PDOException' with message
'SQLSTATE[HY000]: General error: 2014 Cannot execute queries while
other unbuffered queries are active. Consider using
PDOStatement::fetchAll(). Alternatively, if your code is only ever
going to run against mysql, you may enable query buffering by setting
the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute.'
The first thing that is odd, is that I do not get an error on my localhost (wampserver), but I do get it on my web server. The php version on my localhost is 5.3.10, and on my web server it is 5.3.13.
I have read that the source of this error is making a query when data left in the buffer from a previous query. This is not the case for me -- I have echo'd out all of the data and I know for a fact that every row returned in a query is being fetched.
With that said, I have found that changing one of my queries to fetchAll instead of fetch fixes the problem, but it simply makes no since because I know that all of the rows returned are being read. When I used fetchAll for the query (it is being made in a loop), I printed out the array each loop, and only one item was in the array for each query in the loop.
One more piece of information. It's not the query that I changed to fetchAll (which makes the error go away) that throws the PDO error, there is another query later in my php file that throws the error. My file is basically like this:
... code ...
query 1
... code ...
loop
query 2
end loop
... code ...
query 3
If I comment out query 3, there is no error. If I comment out, or change to fetchAll, query 2, there is no error. query 1 has no affect whatsoever.
I would also like to add that I have tried adding LIMIT 1 to all of the queries on the page (at the same time), and the error is still there. I think this proves there is not unread data in the buffer, right?
I'm really confused, so I would appreciate your advice. Before someone asks, I can't post the full code for this, but here is a simplified version of my code:
$stmt = $this->db->prepare('SELECT ... :par LIMIT 1');
makeQuery($stmt, array(':par' => $var));
$row = $stmt->fetch(PDO::FETCH_ASSOC);
$stmt = $this->db->prepare('SELECT ... :par LIMIT 1');
for loop
makeQuery($stmt, array(':par' => $var));
$row2 = $stmt->fetch(PDO::FETCH_ASSOC);
... [use row2] ...
end for loop
$stmt = $this->db->prepare('SELECT ... :par LIMIT 1');
makeQuery($stmt, array(':par' => $var));
$row3 = $stmt->fetch(PDO::FETCH_ASSOC);
Here is makeQuery().
/**************************************************************************************************************
* Function: makeQuery *
* Desc: Makes a PDO query. *
* Pre conditions: The statement/query and an array of named parameters (may be empty) must be passed. *
* Post conditions: The PDO query is executed. Exceptions are caught, displayed, and page execution stopped. *
**************************************************************************************************************/
function makeQuery($stmt, $array, $errMsg = '')
{
try
{
$stmt->execute($array);
}
catch (PDOException $e)
{
print $errMsg != ''?$errMsg:"Error!: " . $e->getMessage() . "<br/>";
die();
}
}
Thanks for your help!
EDIT: I also tried doing the following after query 2 (since that seems to be the source of the problem:
$row2 = $stmt->fetch(PDO::FETCH_ASSOC); var_dump($row2);
The output was:
bool(false)
Have I stumbled across a PDO bug?
You need to fetch until a row fetch attempt fails. I know you may only have one row in the result set and think one fetch is enough, but its not (when you're using unbuffered queries). PDO doesn't know how many rows there are until it reaches the end, where it tries to fetch the next row, but it fails.
You probably have other statements where you didn't fully "fetch until a fetch failed". Yes, I see that you fetch until the fetch failed for one of the statements, but that doesn't mean you did it for all of them.
To clarify -
When you execute a query via execute(), you create a result set that must be fetched from the db into php. PDO can only handle 1 of these "result set in progress of being fetched" at a time (per connection). You need to completely fetch the result set, all the way to the end of it, before you can start fetching a different result set from a different call to execute().
When you "call fetch() until a fetch() fails", the fact that you reached the end of the results is internally noted by PDO when that final call to fetch() fails due to there being no more results. PDO is then satisfied that the results are fully fetched, and it can clean up whatever internal resources between php and the db that were established for that result set, allowing you to make/fetch other queries.
There's other ways to make PDO "call fetch() until a fetch() fails".
Just use fetchAll(), which simply fetches all rows, and so it will hit the end of the result set.
or just call closeCursor()
*if you look at the source for closeCursor(), the default implementation literally just fetches the rows and discards them until it reaches the end. It's written in c obviously, but it more or less does this:
function closeCursor() {
while ($row = $stmt->fetch()) {}
$this->stmtFullyFetched = true;
}
Some db drivers may have a more efficient implementation that doesn't require them to fetch lots of rows that nobody cares about, but that's the default way PDO does it. Anyway...
Normally you don't have these problems when you use buffered queries. The reason is because with buffered queries, right after you execute them, PDO will automatically fully fetch the db results into php memory, so it does the "call fetch() until a fetch() fails" part for you, automatically. When you later call fetch() or fetchAll() yourself, it's fetching results from php memory, not from the db. So basically, the result set is immediately fully fetched when using buffered queries, so there's no opportunity to have more than 1 "result set in progress of being fetched" at the same time (because php is single threaded, so no chance of 2 queries running at the same time).
Given this:
$sql = "select * from test.a limit 1";
$stmt = $dbh->prepare($sql);
$stmt->execute(array());
Ways to fully fetch the result set (assuming you only want the first row):
$row = $stmt->fetch();
$stmt->closeCursor();
or
list($row) = $stmt->fetchAll(); //tricky
or
$row = $stmt->fetch();
while ($stmt->fetch()) {}
After struggling with this issue for days, I finally found that this worked for me:
$db = new PDO ($cnstring, $user, $pwd);
$db->setAttribute (PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true);
This also happen if you are trying to fetch a non SELECT query (Eg - UPDATE/INSERT/ALTER/CREATE). Make sure to use fetch or fetchAll only for SELECT queries.
Possible Duplicate Answer/Question
From PHP, I am calling a SQL stored procedure. The stored procedure checks the database, and either inserts the data if it's new, or modifies data that already exists.
I'm getting an error that one of my parameters is of an incorrect data type. I can't really control this because of where the data is coming from. I am calling the stored procedure hundreds, or thousands of times looping through an array of data, and I only get this error for a couple of records out of the batch.
What is the proper way to handle this error in the stored procedure? If any of the parameters have the incorrect data type, I just want to skip that record and move on to the next record. Each call comes from a foreach loop.
The database is reporting the error and PHP is displaying it. I do not have experience with error handling.
Example PHP Code:
foreach($item_array as $item) {
$id = $item['id'];
$color = $item['color'];
$con = connect()
$query = 'EXECUTE PROCEDURE sp_update_db(:id, :color);'
$params = array(':id' => $id, ':color' => $color);
$stmt = prepare($con, $query);
$result = execute($stmt, $params);
close($con);
}
Running the code I get "Warning: SQL error: [stored procedure a paramater was of the incorrect datatype]".
Looks to me that your proc is not even executed as a result of the wrong parameter being passed; you can only handle this on your php code by catching the exception.
If the proc is in fact being called, but simply failling inside the procedure due to some sort of data type mismatch, you can use
BEGIN TRY
-- your proc statements here
END TRY
BEGIN CATCH
END CATCH
Documentation here.
UPDATE
Since you said that you are calling the proc once per each record that you need to process, you need to catch the error on the PHP side. You can use try/catch blocks on PHP. See here.
Basically, you'd need to have the try/catch block inside your foreach loop enclosing only the part that calls the stored procedure; however, I would just have an if statement before the stored procedure call that makes sure all the parameters that will be passed to the proc are of the expected type and lenght. For example, if stored procedure expectes parameter #a of type int, I would prevent the proc from being called at all if the parameter that is about to be passed is not a number or an empty string.
UPDATE 2
Based on sample php (Warning: I am not a PHP coder), seems like this will work:
try{
$result = execute($stmt, $params);
}
catch (Exception $e) {
}
But again, if you know the data types expected by the proc, why not have an if instead of the try/catch?
We have a function used within our PHP/MySQL application which returns basic configuration information, it contains a simple select query and looks like this:
public function getConfigurationValue($field)
{
$res = mysql_query("SELECT `cfg_value` FROM `ls_config` WHERE `cfg_name` = '".mysql_real_escape_string($field)."'");
$cfg = htmlspecialchars(mysql_result($res,0));
return $cfg;
}
This problem we are having is that occasionally, seemingly at random, this query throws a mysql error on mysql_result saying that "supplied argument is not a valid mysql result resource". In our debugging we have determined though that this is not because $field is not being passed. Essentially, for a reason we cannot determine a perfectly valid query fails and returns no results causing an empty result set and the subsequent error. If the error was due to the mysql connection failing the script would have died well before this. Also, this function may be called 50-100 times on some page loads but it only tends to fail once on each load.
Please let me know if you need any other information to work this out.
Thanks.
searching for php "supplied argument is not a valid mysql result resource" reveals that to get the actual error, you'd need to call mysql_error, and the error that you get is because the result of the query is FALSE - this value not being a valid mysql result resource.
i.e. in short you have something like:
$res = FALSE; # should contain the mysql result but does not, due to error.
$cfg = htmlspecialchars(mysql_result($res,0)); # the attempt to call mysql_result on invalid argument errors out.
So you'd want to use something like this:
$query = "SELECT * FROM cats WHERE id=$id";
$qr1 = mysql_query ($query)
or die ("Query failed: " . mysql_error() . " Actual query: " . $query);
You might want to give this a shot and see what the underlying error message says.
Given that the error is "MySQL server has gone away", There can be multitude of reasons for it - this article would be a good start to investigate. Searching suggests also some php-related and stack-specific bugs, so it looks like you might need to debug it with a closer attention.
Maybe try to duplicate the setup on another box and then start experimenting with the versions/settings, and see if any of the already reported scenarios match your case. Unfortunately, seems there's no single simple answer to this.
Stored procs in SQL Server sometimes finish with a return code, as opposed to a recordset of data. I've seen ASP code that's able to get this return code, but I can't figure out how to get this code with PHP's mssql driver.
mssql_get_last_message() always returns nothing, and I'm thinking it's because it only returns the very last line that came from the server. When we run the proc in another application (outside PHP), there is blank line following the return code.
Has anyone figured out how to get return codes from SQL stored procs using PHP's mssql driver?
Are you talking about SQL Server error codes, e.g. RAISERRROR or other failures? If so, last time I checked in PHP you need to ask for ##ERROR (e.g. select ##error) instead.
If it is a return code, you must explicitly catch it, e.g.
DECLARE #return_code INT
EXEC #return_code = your_stored_procedure 1123
SELECT #return_code
To get a numeric error code from mssql you can do a select that looks something like
SELECT ##ERROR AS ErrorCode
Which SHOULD return the correct error code.