In my local/development environment, the MySQLi query is performing OK. However, when I upload it on my web host environment, I get this error:
Fatal error: Call to a member function bind_param() on a non-object in...
Here is the code:
global $mysqli;
$stmt = $mysqli->prepare("SELECT id, description FROM tbl_page_answer_category WHERE cur_own_id = ?");
$stmt->bind_param('i', $cur_id);
$stmt->execute();
$stmt->bind_result($uid, $desc);
To check my query, I tried to execute the query via control panel phpMyAdmin and the result is OK.
TL;DR
Always have mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT); in your mysqli connection code and always check the PHP errors.
Always replace every PHP variable in the SQL query with a question mark, and execute the query using prepared statement. It will help to avoid syntax errors of all sorts.
Explanation
Sometimes your MySQLi code produces an error like mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean given..., Call to a member function bind_param()... or similar. Or even without any error, but the query doesn't work all the same. It means that your query failed to execute.
Every time a query fails, MySQL has an error message that explains the reason. In the older PHP versions such errors weren't transferred to PHP, and all you'd get is a cryptic error message mentioned above. Hence it is very important to configure PHP and MySQLi to report MySQL errors to you. And once you get the error message, fixing it will be a piece of cake.
How to get the error message in MySQLi
First of all, always have this line before MySQLi connect in all your environments:
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
After that, all MySQL errors will be transferred into PHP exceptions. An uncaught exception, in turn, makes a PHP fatal error. Thus, in case of a MySQL error, you'll get a conventional PHP error. That will instantly make you aware of the error cause. And the stack trace will lead you to the exact spot where the error occurred.
How to get the error message from PHP
Here is a gist of my article on PHP error reporting:
Reporting errors on a development and live servers must be different. On the development server it is convenient to have errors shown on-screen, but on a live server error messages must be logged instead, so you could find them in the error log later.
Therefore, you must set corresponding configuration options to the following values:
On a development server
error_reporting should be set to E_ALL value;
log_errors should be set to 1 (it is convenient to have logs on a development PC too)
display_errors should be set to 1
On a production server
error_reporting should be set to E_ALL value;
log_errors should be set to 1
display_errors should be set to 0
After that, when MySQL query fails, you will get a PHP error that explains the reason. On a live server, in order to get the error message, you'll have to check the error log.
In case of AJAX call, on a dev server open DevTools (F12), then Network tab. Then initiate the request which result you want to see, and it will appear in the Network tab. Click on it and then the Response tab. There you will see the exact output. On a live server check the error log.
How to actually use it
Just remove any code that checks for the error manually, all those or die(), if ($result), try..catch and such. Simply write your database interaction code right away:
$stmt = $this->con->prepare("INSERT INTO table(name, quantity) VALUES (?,?)");
$stmt->bind_param("si", $name, $quantity);
$stmt->execute();
Again, without any conditions around. If an error occurs, it will be treated like any other error in your code. For example, on a development PC it will just appear on-screen, while on a live site it will be logged for the programmer, whereas for the user's convenience you could use an error handler (but that's a different story which is off topic for MySQLi, but you may read about it in the article linked above).
What to do with the error message you get
First of all you have to locate the problem query. The error message contains the file name and the line number of the exact spot where the error occurred. For the simple code that's enough, but if your code is using functions or classes you may need to follow the stack trace to locate the problem query.
After getting the error message, you have to read and comprehend it. It sounds too obvious if not condescending, but learners often overlook the fact that the error message is not just an alarm signal, but it actually contains a detailed explanation of the problem. And all you need is to read the error message and fix the issue.
Say, if it says that a particular table doesn't exist, you have to check spelling, typos, and letter case. Also you have to make sure that your PHP script connects to a correct database
Or, if it says there is an error in the SQL syntax, then you have to examine your SQL. And the problem spot is right before the query part cited in the error message.
If you don't understand the error message, try to google it. And when browsing the results, stick to answers that explain the error rather than bluntly give the solution. A solution may not work in your particular case, but the explanation will help you to understand the problem and make you able to fix the issue by yourself.
You have to also trust the error message. If it says that number of tokens doesn't match the number of bound variables then it is so. The same goes for the absent tables or columns. Given the choice, whether it's your own mistake or the error message is wrong, always stick to the former. Again it sounds condescending, but hundreds of questions on this very site prove this advise extremely useful.
A list of things you should never ever do in regard of error reporting
Never use an error suppression operator (#)! It makes a programmer unable read the error message and therefore unable to fix the error
Do not use die() or echo or any other function to print the error message on the screen unconditionally. PHP can report errors by itself and do it the right way depends on the environment - so just leave it for PHP.
Do not add a condition to test the query result manually (like if($result)). With error exceptions enabled such condition will just be useless.
Do not use the try..catch operator for echoing the error message. This operator should be used to perform some error handling, like a transaction rollback. But never use it just to report errors - as we learned above, PHP can already do it, the right way.
P.S.
Sometimes there is no error, but no results either. Then it means, there is no data in the database to match your criteria. In this case you have to admit this fact, even if you can swear the data and the criteria are all right. They are not. You have to check them again.
I've got an article that can help in this matter, How to debug database interactions. Although it is written for PDO, the principle is the same. Just follow those instructions step by step and either have your problem solved or have an answerable question for Stack Overflow.
In using realbrowserlocusts class it appears that I'm limited in any exception handling.
The only reference that partially works is: self.client.wait.until(EC.visibility_of_element_located ....
In a failed condition where the element is not found the script simply starts over again. With the script I'm working with I need to maintain a solid session state; I need to throw and exception(report an error), log the user out and then let the script start over again. I've been testing out the behavior with the locust.py script that Nick B. created with several approaches to "try, except" and they work running without realbrowserlocusts (selenium only) but with it the execution just stops.
Any examples would be greatly appreciated.
In its current format I've been able to run 3x the amount of a browser-based load per/agent/slave than our commercial tool. My goal is to replace it with a locust/selenium approach.
locust-plugins's WebdriverUser has a little bit better exception handling I think. A failure to find an element will log a failed request and if you use RescheduleTaskOnFail (as in the the example) it will restart the task when that happens.
https://github.com/SvenskaSpel/locust-plugins/blob/master/examples/webdriver_ex.py
I'm trying to make a community connector to connect my database in BigQuery to data studio with the service account that I hooked up as the Owner/DataViewer/JobUser of the BigQuery project. I know that the service account works when connecting to BigQuery because I've tested it elsewhere. I copied from the connector code from this tutorial (https://developers.google.com/datastudio/solution/blocks/using-service-accounts) almost exactly, replacing the SQL string with my query and adding some different query parameters. I also stored the service account's credentials in my script properties by pasting the json object and storing it like:
var service_account_creds_obj = {
"type": "service_account",
"project_id": ...
...
}
scriptProperties.setProperty('SERVICE_ACCOUNT_CREDS', JSON.stringify(service_account_creds_obj));
However, I always get stuck in the flow when my getData function calls getOauthService().getAccessToken(), which doesn't ever successfully return. When I create a report using the connector, I get this error: "Access not granted or expired." I can't find the documentation for getAccessToken and I'm having trouble understanding why it won't terminate. I can see that it doesn't return because a console.log immediately before that line displays but it never gets to the log on the next line. Then my try-catch block catches the error that I'm seeing. Note that my getOauthService function is exactly the same as the one from the documentation/tutorial example, except that I've played around with the input text in the call to createService. That input text shouldn't really matter though right?
Please, I've been trying to debug this for hours, but the documentation on this is pretty horrible, and it's really hard to debug since the flow of the code is handled in the background and stackdriver logging is really buggy.
I figured out my problem. The documentation posted above said to set the OAuth2 scope to https://www.googleapis.com/auth/bigquery.readonly. However, I naively included
"oauthScopes": ["https://www.googleapis.com/auth/bigquery.readonly"]
in my manifest file. Meanwhile, the code I copied over from the documentation already included this line:
.setScope(['https://www.googleapis.com/auth/bigquery.readonly']);
So I'm not sure exactly why this caused a problem. But it must have prevented the OAuth2.createService function from properly getting set.
I am using ssis event handler to trigger an email whenever an error occured in the entire package(PACKAGE+ONEEROR). Here number of emails triggered is equal to number of errors generated.How can I restrict it to one mail eventhough the same error occured 10 times.
Please suggest....
You have a few options. The problem with setting an ONERROR email at the package level is that it will send an email for each error the package encounters. This gets ugly if you have a deep level transform fail, which will error as it fails back up to the package level.
I suggest that you either:
1) Setup ONERROR events at the task level and remove the package level event. Usually this will be good enough. Most tasks will only have one error to report. Be careful with Data Flows, they can act in a similar fashion as the package level events.
2) Setup some sort of advance logging. I’ve seen this done several ways. I’ve seen some people setup Script tasks to log the errors (at the task level) to a variable, and then send a final email containing the variable in the body (at control flow level). I have also seen people call stored procedures (at the task level and package level) for each error that occurs. The sproc would log errors to the DB and allow the package to continue on to the next step/container. The logged errors can then be dumped into a csv and emailed as an attachment.
If you like your current setup, you can try changing the error properties for each container/task. I haven't ever done this, but I do know you can change the way tasks handle errors! I don't like this option because you would possibly be missing errors (maybe? kind of guessing).
update From another solution - If you want to keep your current email ONERROR and simply prevent certain errors from "bubbling" up and sending emails, you can follow this link to learn how to gracefully handle errors. You could prevent certain tasks errors from reaching your ONERROR event at the package level. good luck.
I want to execute a job when ever a file is dropped into a particular folder.
I found some articles that showed me how I can do it on SQL Server.
I created a alert type: WMI Event Alert
For the name space its the SQL instance which comes automatically as \\.\root\Microsoft\SqlServer\ServerEvents\MSSQLSERVER
On the Query section - I wrote the below query ,
SELECT *
FROM __InstanceCreationEvent
WITHIN 1
WHERE TargetInstance ISA 'CIM_DataFile'
AND TargetInstance.Name = ‘c:\\TestFolder\’ `
The error message returned is:
Cannot create new alert.
ADDITIONAL INFORMATION:
Create failed for Alert 'AlertTest'. (Microsoft.SqlServer.Smo)
For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=10.50.2425.0+((KJ_PCU_Main).110406-2044+)&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.FailedOperationExceptionText&EvtID=Create+Alert&LinkId=20476
An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)
SQLServerAgent Error: WMI error: 0x80041058
The #wmi_query could not be executed in the #wmi_namespace provided. Verify that an event class selected in the query exists in the namespace and that the query has the correct syntax. (Microsoft SQL Server, Error: 22022)
For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=10.50.2425&EvtSrc=MSSQLServer&EvtID=22022&LinkId=20476
Please may you advise if my Query is correct and if there is anything else I need to check?
Thanks a lot in advance.
You are using the wrong namespace, the CIM_DataFile WMI class is part of the \root\CIMV2 namespace and not of \root\Microsoft\SqlServer\ServerEvents\MSSQLSERVER
In this case, the answer from RRUZ is correct. However there are other possible causes of this error message:
The #wmi_query could not be executed in the #wmi_namespace provided.
One possible reason is the account that runs the Windows service "Windows Management Instrumentation" is disabled as a SQL login. (If you are running SQL 2012+, look for the login 'NT SERVICE\winmgmt').
(Source: Blog by 'rahmanagoro' )
Edit 2020-05-29: I've made a more comprehensive answer to this question on the DBA forum.
Another possible fix is to restart the "Windows Management Instrumentation" service. No idea what leads to the problem, but restarting the service fixes it. I've seen this twice, both times on Windows Server 2008 R2 Standard Edition x64.
Edit 2020-05-29: I've made a more comprehensive answer to this question on the DBA forum.