I am having trouble with the query in this code. The problem is one I have had before, the $num = mysql_num_rows($result); part gives me a MySQL error saying it expected a resource. Usually when I have this error it is because I misplaced a single quote some where, but after looking I cannot find any problem, though this query is a bit more complex than what I usually have to deal with.
//connect to the database and stuff
$last_year = idate("Y")-1;
$month = date("m");
$day = date("d");
$query = "SELECT bills.b_id, bills.c_id, bills.grand_total, bills.void, bills.date_added,
customers.b_name, customers.l_name, customers.f_name, customers.phone
FROM bills, customers
WHERE bills.c_id = customers.c_id
AND bills.void = '0'
AND date_added BETWEEN '".$last_year."-".$month."-".$day."' AND CURDATE()";
$result = mysql_query($query);
mysql_close($link);
$num = mysql_num_rows($result);
EDIT:
Although I already know the mysql_close() function is not the problem I went ahead and removed it and my code still does not work. This EXACT same code (other than the query) works in nearly a dozen other pages. The problem is in the query, the MySQL error (as stated before) is mysql_num_rows() expects parameter 1 to be resource. I am working on getting the specific error now.
Add some error handling to your code.
$result = mysql_query($query);
if ( !$result ) {
echo 'the query failed: ', mysql_error();
die;
}
(in "real" production code you might not want to display the actual query and error message to just any arbitrary user though).
see also: http://docs.php.net/mysql_error
Check to see if there were mysql errors. If you don't already have error reporting turned on, turn it on for development (error_reporting(E_ALL);).
Try waiting to close your mysql connection until after you're done with the result sets.
Try with the mysql_close() function at the end. If you close the mysql connection, mysql_num_rows() is not going to work
$num = mysql_num_rows($result);
.
.
//Any others mysql operations
.
.
mysql_close($link);
You close link to mysql before retrieving query results. That's the problem. Just don't use mysql_close() as PHP can automatically handle it.
"not a resource" error means your query failed.
change your mysql_query call in that manner
$result = mysql_query($query) or trigger_error(mysql_error().$query);
and see what's wrong with your query.
always do it this way to keep in touch with every error may occur
Related
I'm completely out of ideas as to what's happening here.
Here's my code:
$sid = "123";
$sid_query_conf = mysql_query("SELECT email FROM users WHERE sid='$sid'");
if(!$sid_query_conf)
die(mysql_error());
$result = mysql_fetch_assoc($sid_query_conf);
if(mysql_num_rows($result) == 0)
die("Error processing your details");
It's consistently returning "Error processing your details" where is phpMyAdmin I get the result that I'm looking for. There's even 1 query before this so I know that the connection it works in that respect.
I've even tried to just select everything from the table and it's still returning no rows. mysql_fetch_result also did nothing.
I could really do with some help as to what's happening to make it not work like this.
I believe mysql_num_rows($result) should be mysql_num_rows($sid_query_conf)
Also you shouldnt be using mysql_* functions anymore as they are deprecated, use PDO or mysqli instead.
http://php.net/manual/en/function.mysql-num-rows.php
I am attempting to get the following PDO statement to work and running into issues. When I am trying to get the number of rows, I keep getting 0, yet I know there should be 1 row. When I ran it as a mysqli statement( before trying to change it to PDO) it worked perfectly.
Here is the code:
require_once ('pdo.php');
$isbn = $_POST['isbn'];
// check to see if the isbn is a "problem" isbn or not
$problem = $conn->prepare("select isbn, note from problem where isbn = :isbn");
$problem->bindParam(":isbn", $isbn);
$problem->execute();
print_r($problem);
$num_rows = $problem->rowCount();
print_r($num_rows); die;
EDIT: Here is pdo.php:
<?php
function db_connect()
{
$db = new PDO("mysql:host=localhost; db=bookcell_BCOS_final", "xxxxx", "xxxxx");
return($db);
}
?>
I know that my connection works, but I get 0 for $num_rows. What mistakes am I making here?
Besides a little quirk and a optimalisation your code looks fine to me. The posted value isbn could be the reasong that you are getting no data:
$problem = $conn->prepare("select isbn, note from problem where isbn = :isbn");
$problem->bindParam(":isbn", $_POST['isbn'], PDO::PARAM_STR); // <-- thats what parameter binding is for
$problem->execute();
print_r($problem);
$num_rows = $problem->rowCount(); // <-- gives the number of rows, not columnCOunt
print_r($num_rows); die;
The Syntax for $num_rows = $problem->columnCount(); is totally correct. You may try,
$problem->execute(array("isbn" => $isbn));
instead of bindParam.
for getting the no. of rows, you need to use pdo::rowCount() -- manual here
In PDO to verfiy if your execute statement did work, check the return value (bool):
$success = $problem->execute();
if (!$success) {
$arr = $problem->errorInfo();
print_r($arr);
}
Also you might be looking for rowCount() instead of columnCount() but I think the error handling is your furthermost issue.
Additionally you can make PDO throw an exception each time an error appears, compare:
Switching from PHP's mysql extension to PDO. Extend class to reduce lines of code
How do I raise PDOException?
Depending on the database driver and the mode it's running, PDO may not be able to give you a row count. Look carefully at the documentation for PDOStatement::rowCount():
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.
This is because in many cases the database uses a cursor rather than fetching the full results and buffering them (which is how the old mysql_* functions behave). In this case the database doesn't know how many rows there are until you have looked at all the rows. Think of a cursor as something like a filesystem pointer--you can't know the filesize until you seek to the end of the file.
At my workplace, we were having problems with a certain field. From time to time we need to suspend someone from a mailing list, and to do that, we would just update their record to make the suspend field = Y.
That works no problem in phpMyAdmin, but when we use the crud pages for the staff, sometimes it fails to update, leaving the value of Suspend = N. After looking at the code, I wanted to know if the following line could be the source of the problem.
$rs = mysql_query($sql, $conn) or die("Query has Failed : $sql");
Everything else before it looks good, and it is the last line in the script. Now, I would think that this shouldn't work, but it does. This will run the query. I would think that it would only work if it was
mysql_query($sql, $conn) or die("Query has Failed : $sql");
But it seems to work fine on most occasions. Only every now and then it doesn't work. Could this be the cause of the problem? One last bit of information, we are using MyIsam for the engine.
I would appreciate any help you could give!
mysql_query will return a value whether you're assigning that return to a variable or not. By PHP's operator precedence rules, the first statement is seen as:
$rs = (
(mysql_query($sql, $conn))
or
(die("Query has Failed..."))
);
What's the query look like? Remember that mysql_query can return a "success" status, even though the query has failed to do what you intended. e.g. UPDATE ... SET ... WHERE (somefield = value_that_doesnt_exist);. The query didn't do what you wanted, but it also wasn't invalid, so mysql_query will not return FALSE and won't trigger the or die(...).
We have a function used within our PHP/MySQL application which returns basic configuration information, it contains a simple select query and looks like this:
public function getConfigurationValue($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: " . $query);
You might want to give this a shot and see what the underlying error message says.
Given that the error is "MySQL server has gone away", There can be multitude of reasons for it - this article would be a good start to investigate. Searching suggests also some php-related and stack-specific bugs, so it looks like you might need to debug it with a closer attention.
Maybe try to duplicate the setup on another box and then start experimenting with the versions/settings, and see if any of the already reported scenarios match your case. Unfortunately, seems there's no single simple answer to this.
I'm having trouble with this PHP script where I get the error
Fatal error: Maximum execution time of 30 seconds exceeded in /var/www/vhosts/richmondcondo411.com/httpdocs/places.php on line 77
The code hangs here:
function getLocationsFromTable($table){
$query = "SELECT * FROM `$table`";
if( ! $queryResult = mysql_query($query)) return null;
return mysql_fetch_array($queryResult, MYSQL_ASSOC);
}
and here (so far):
function hasCoordinates($houseNumber, $streetName){
$query = "SELECT lat,lng FROM geocache WHERE House = '$houseNumber' AND StreetName = '$streetName'";
$row = mysql_fetch_array(mysql_query($query), MYSQL_ASSOC);
return ($row) ? true : false;
}
both on the line with the mysql_query() call.
I know I use different styles for each code snippet, it's because I've been playing with the first one trying to isolate the issue.
The $table in the first example is 'school' which is a table which definitely exists.
I just don't know why it sits there and waits to time out instead of throwing an error back at me.
The mysql queries from the rest of the site are working properly. I tried making sure I was connected like this
//connection was opened like this:
//$GLOBALS['dbh']=mysql_connect ($db_host, $db_user, $db_pswd) or die ('I cannot connect to the database because: ' . mysql_error());
if( ! $GLOBALS['dbh']) return null;
and it made it past that fine. Any ideas?
Update
It's not the size of the tables. I tried getting only five records and it still timed out. Also, with this line:
$query = "SELECT lat,lng FROM geocache WHERE House = '$houseNumber' AND StreetName = '$streetName'";
it is only looking for one specific record and this is where it's hanging now.
It sounds like MySQL is busy transmitting valid data back to PHP, but there's so much of it that there isn't time to finish the process before Apache shuts down the PHP process for exceeding its maximum execution time.
Is it really necessary to select everything from that table? How much data is it? Are there BLOB or TEXT columns that would account for particular lag?
Analyzing what's being selected and what you really need would be a good place to start.
Time spent waiting for mysql queries to return data does not count towards the execution time. See here.
The problem is most likely somewhere else in the code - the functions that you are blaming are possibly called in an infinite loop. Try commenting out the mysql code to see if I'm right.
Does your code timeout trying to connect or does it connect and hang on the query?
If your code actually gets past the mysql_query call (even if it has to wait a long time to timeout) then you can use the mysql_error function to determine what happened:
mysql_query("SELECT * FROM table");
echo mysql_errno($GLOBALS['dbh']) . ": " . mysql_error($GLOBALS['dbh']) . "\n";
Then, you can use the error number to determine the detailed reason for the error: MySQL error codes
If your code is hanging on the query, you might try describing and running the query in a mysql command line client to see if it's a data size issue. You can also increase the maximum execution time to allow the query to complete and see what's happening:
ini_set('max_execution_time', 300); // Allow 5 minutes for execution
I don't know about the size of your table, but try using LIMIT 10 and see if still hangs.
It might be that your table is just to big to fetch it in one query.
Unless the parameters $houseNumber and $streetName for hasCoordinates() are already sanitized for the MySQL query (very unlikely) you need to treat them with mysql_real_escape_string() to prevent (intentional or unintentional) sql injections. For mysql_real_escape_string() to work properly (e.g. if you have changed the charset via mysql_set_charset) you should also pass the MySQL connection resource to the function.
Is the error reporting set to E_ALL and do you look at the error.log of the webserver (or have set display_erorrs=On)?
Try this
function hasCoordinates($houseNumber, $streetName) {
$houseNumber = mysql_real_escape_string($houseNumber);
$streetName = mysql_real_escape_string($streetName);
$query = "
EXPLAIN SELECT
lat,lng
FROM
geocache
WHERE
House='$houseNumber'
AND StreetName='$streetName'
";
$result = mysql_query($query) or die(mysql_error());
while ( false!==($row=mysql_fetch_array($result, MYSQL_ASSOC)) ) {
echo htmlspecialchars(join(' | ', $row)), "<br />\n";
}
die;
}
and refer to http://dev.mysql.com/doc/refman/5.0/en/using-explain.html to interpret the output.
-If you upped the execution time to 300 and it still went through that 300 seconds, I think that by definition you've got something like an infinite loop going.
-My first suspect would be your php code since mysql is used to dealing with large sets of data, so definitely make sure that you're actually reaching the mysql query in question (die right before it with an error message or something).
-If that works, then try actually running that query with known data on your database via some database gui or via the command line access to the database if you have that, or replacing the code with known good numbers if you don't.
-If the query works on it's own, then I would check for accidental sql injection coming from with the $houseNumber or $streetName variables, as VolkerK mentioned.