preventing a specific mysqli_fetch_assoc() from sending a warning - warnings

I use a specific query that is acting weird: On my local environment, it works perfect and sends no warning. Online, the query itself works fine, however, mysqli_fetch_assoc($result) is producing the 'mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean given' warning.
I never occured a query that was causing this warning AND got the right info from the DB. This is why I tend to believe the problem is not in the code.
Is there a way to shut off the warnings only for this one specific query?
EDIT -
PROBLEM SOLVED.
it is really strange to me, but the problem was an incorrect script src path for dojo.js.
I have no idea what's the connection, but fixing the path prevented mysqli warnings.


You should be checking if $result == false before you call mysqli_fetch_assoc. Generally you catch it first by checking mysqli_connect_errno() but the general idiom is to proactively check before fetching rows

Related

How to display, why mysql query not working? [duplicate]

This is my PHP SQL statement and it's returning false while var dumping
$sql = $dbh->prepare('INSERT INTO users(full_name, e_mail, username, password) VALUES (:fullname, :email, :username, :password)');
$result = $sql->execute(array(
':fullname' => $_GET['fullname'],
':email' => $_GET['email'],
':username' => $_GET['username'],
':password' => $password_hash));

TL;DR
Always have set PDO::ATTR_ERRMODE to PDO::ERRMODE_EXCEPTION in your PDO connection code. It will let the database tell you what the actual problem is, be it with query, server, database or whatever. Also, make sure you can see PHP errors in general.
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 PDO code produces an error like Call to a member function execute() 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. Unfortunately, by default such errors are not transferred to PHP, and all you have is a silence or a cryptic error message mentioned above. Hence it is very important to configure PHP and PDO to report you MySQL errors. And once you get the error message, it will be a no-brainer to fix the issue.
In order to get the detailed information about the problem, either put the following line in your code right after connect
$dbh->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
(where $dbh is the name of your PDO instance variable) or - better - add this parameter as a connection option. After that all database errors will be translated into PDO exceptions which, if left alone, would act just as regular PHP errors.
After getting the error message, you have to read and comprehend it. It sounds too obvious, but learners often overlook the meaning of the error message. Yet most of time it explains the problem pretty straightforward:
Say, if it says that a particular table doesn't exist, you have to check spelling, typos, 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.
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. Same goes for 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 advice extremely useful.
Note that in order to see PDO errors, you have to be able to see PHP errors in general. To do so, you have to configure PHP depends on the site environment:
on a development server it is very handy to have errors right on the screen, for which displaying errors have to be turned on:
error_reporting(E_ALL);
ini_set('display_errors',1);
while on a live site, all errors have to be logged, but never shown to the client. For this, configure PHP this way:
error_reporting(E_ALL);
ini_set('display_errors', 0);
ini_set('log_errors', 1);
Note that error_reporting should be set to E_ALL all the time.
Also note that despite the common delusion, no try-catch have to be used for the error reporting. PHP will report you PDO errors already, and in a way better form. An uncaught exception is very good for development, yet if you want to show a customized error page, still don't use try catch for this, but just set a custom error handler. In a nutshell, you don't have to treat PDO errors as something special but regard them as any other error in your code.
P.S.
Sometimes there is no error but no results either. Then it means, there is no data to match your criteria. So 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 short answer that would help you to pinpoint the matching issue, Having issue with matching rows in the database using PDO. Just follow this instruction, and the linked tutorial step by step and either have your problem solved or have an answerable question for Stack Overflow.

Some time ago I had the same problem of not seeing any error messages from mysql. After a research it turned out that the problem has got nothing to do with PHP itself, but with mysql server configuration. The default value of the variable lc_messages_dir pointed to non existing directory. After adding a line in mysqld.cnf, then restarted the mysql server, and finally I was able to see the error messages. For me the following was the right one:
lc_messages_dir=/usr/share/mysql
It is described in the mysql reference manual: https://dev.mysql.com/doc/refman/5.7/en/error-message-language.html

Building a query in PDO with parameters for table name [duplicate]

This is my PHP SQL statement and it's returning false while var dumping
$sql = $dbh->prepare('INSERT INTO users(full_name, e_mail, username, password) VALUES (:fullname, :email, :username, :password)');
$result = $sql->execute(array(
':fullname' => $_GET['fullname'],
':email' => $_GET['email'],
':username' => $_GET['username'],
':password' => $password_hash));

TL;DR
Always have set PDO::ATTR_ERRMODE to PDO::ERRMODE_EXCEPTION in your PDO connection code. It will let the database tell you what the actual problem is, be it with query, server, database or whatever. Also, make sure you can see PHP errors in general.
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 PDO code produces an error like Call to a member function execute() 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. Unfortunately, by default such errors are not transferred to PHP, and all you have is a silence or a cryptic error message mentioned above. Hence it is very important to configure PHP and PDO to report you MySQL errors. And once you get the error message, it will be a no-brainer to fix the issue.
In order to get the detailed information about the problem, either put the following line in your code right after connect
$dbh->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
(where $dbh is the name of your PDO instance variable) or - better - add this parameter as a connection option. After that all database errors will be translated into PDO exceptions which, if left alone, would act just as regular PHP errors.
After getting the error message, you have to read and comprehend it. It sounds too obvious, but learners often overlook the meaning of the error message. Yet most of time it explains the problem pretty straightforward:
Say, if it says that a particular table doesn't exist, you have to check spelling, typos, 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.
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. Same goes for 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 advice extremely useful.
Note that in order to see PDO errors, you have to be able to see PHP errors in general. To do so, you have to configure PHP depends on the site environment:
on a development server it is very handy to have errors right on the screen, for which displaying errors have to be turned on:
error_reporting(E_ALL);
ini_set('display_errors',1);
while on a live site, all errors have to be logged, but never shown to the client. For this, configure PHP this way:
error_reporting(E_ALL);
ini_set('display_errors', 0);
ini_set('log_errors', 1);
Note that error_reporting should be set to E_ALL all the time.
Also note that despite the common delusion, no try-catch have to be used for the error reporting. PHP will report you PDO errors already, and in a way better form. An uncaught exception is very good for development, yet if you want to show a customized error page, still don't use try catch for this, but just set a custom error handler. In a nutshell, you don't have to treat PDO errors as something special but regard them as any other error in your code.
P.S.
Sometimes there is no error but no results either. Then it means, there is no data to match your criteria. So 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 short answer that would help you to pinpoint the matching issue, Having issue with matching rows in the database using PDO. Just follow this instruction, and the linked tutorial step by step and either have your problem solved or have an answerable question for Stack Overflow.

Some time ago I had the same problem of not seeing any error messages from mysql. After a research it turned out that the problem has got nothing to do with PHP itself, but with mysql server configuration. The default value of the variable lc_messages_dir pointed to non existing directory. After adding a line in mysqld.cnf, then restarted the mysql server, and finally I was able to see the error messages. For me the following was the right one:
lc_messages_dir=/usr/share/mysql
It is described in the mysql reference manual: https://dev.mysql.com/doc/refman/5.7/en/error-message-language.html

Is there a conflict in MSQL & MySQL/PDO connections? [duplicate]

This is my PHP SQL statement and it's returning false while var dumping
$sql = $dbh->prepare('INSERT INTO users(full_name, e_mail, username, password) VALUES (:fullname, :email, :username, :password)');
$result = $sql->execute(array(
':fullname' => $_GET['fullname'],
':email' => $_GET['email'],
':username' => $_GET['username'],
':password' => $password_hash));

TL;DR
Always have set PDO::ATTR_ERRMODE to PDO::ERRMODE_EXCEPTION in your PDO connection code. It will let the database tell you what the actual problem is, be it with query, server, database or whatever. Also, make sure you can see PHP errors in general.
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 PDO code produces an error like Call to a member function execute() 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. Unfortunately, by default such errors are not transferred to PHP, and all you have is a silence or a cryptic error message mentioned above. Hence it is very important to configure PHP and PDO to report you MySQL errors. And once you get the error message, it will be a no-brainer to fix the issue.
In order to get the detailed information about the problem, either put the following line in your code right after connect
$dbh->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
(where $dbh is the name of your PDO instance variable) or - better - add this parameter as a connection option. After that all database errors will be translated into PDO exceptions which, if left alone, would act just as regular PHP errors.
After getting the error message, you have to read and comprehend it. It sounds too obvious, but learners often overlook the meaning of the error message. Yet most of time it explains the problem pretty straightforward:
Say, if it says that a particular table doesn't exist, you have to check spelling, typos, 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.
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. Same goes for 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 advice extremely useful.
Note that in order to see PDO errors, you have to be able to see PHP errors in general. To do so, you have to configure PHP depends on the site environment:
on a development server it is very handy to have errors right on the screen, for which displaying errors have to be turned on:
error_reporting(E_ALL);
ini_set('display_errors',1);
while on a live site, all errors have to be logged, but never shown to the client. For this, configure PHP this way:
error_reporting(E_ALL);
ini_set('display_errors', 0);
ini_set('log_errors', 1);
Note that error_reporting should be set to E_ALL all the time.
Also note that despite the common delusion, no try-catch have to be used for the error reporting. PHP will report you PDO errors already, and in a way better form. An uncaught exception is very good for development, yet if you want to show a customized error page, still don't use try catch for this, but just set a custom error handler. In a nutshell, you don't have to treat PDO errors as something special but regard them as any other error in your code.
P.S.
Sometimes there is no error but no results either. Then it means, there is no data to match your criteria. So 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 short answer that would help you to pinpoint the matching issue, Having issue with matching rows in the database using PDO. Just follow this instruction, and the linked tutorial step by step and either have your problem solved or have an answerable question for Stack Overflow.

Some time ago I had the same problem of not seeing any error messages from mysql. After a research it turned out that the problem has got nothing to do with PHP itself, but with mysql server configuration. The default value of the variable lc_messages_dir pointed to non existing directory. After adding a line in mysqld.cnf, then restarted the mysql server, and finally I was able to see the error messages. For me the following was the right one:
lc_messages_dir=/usr/share/mysql
It is described in the mysql reference manual: https://dev.mysql.com/doc/refman/5.7/en/error-message-language.html

PHP PDO - Empty Page [duplicate]

This is my PHP SQL statement and it's returning false while var dumping
$sql = $dbh->prepare('INSERT INTO users(full_name, e_mail, username, password) VALUES (:fullname, :email, :username, :password)');
$result = $sql->execute(array(
':fullname' => $_GET['fullname'],
':email' => $_GET['email'],
':username' => $_GET['username'],
':password' => $password_hash));

TL;DR
Always have set PDO::ATTR_ERRMODE to PDO::ERRMODE_EXCEPTION in your PDO connection code. It will let the database tell you what the actual problem is, be it with query, server, database or whatever. Also, make sure you can see PHP errors in general.
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 PDO code produces an error like Call to a member function execute() 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. Unfortunately, by default such errors are not transferred to PHP, and all you have is a silence or a cryptic error message mentioned above. Hence it is very important to configure PHP and PDO to report you MySQL errors. And once you get the error message, it will be a no-brainer to fix the issue.
In order to get the detailed information about the problem, either put the following line in your code right after connect
$dbh->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
(where $dbh is the name of your PDO instance variable) or - better - add this parameter as a connection option. After that all database errors will be translated into PDO exceptions which, if left alone, would act just as regular PHP errors.
After getting the error message, you have to read and comprehend it. It sounds too obvious, but learners often overlook the meaning of the error message. Yet most of time it explains the problem pretty straightforward:
Say, if it says that a particular table doesn't exist, you have to check spelling, typos, 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.
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. Same goes for 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 advice extremely useful.
Note that in order to see PDO errors, you have to be able to see PHP errors in general. To do so, you have to configure PHP depends on the site environment:
on a development server it is very handy to have errors right on the screen, for which displaying errors have to be turned on:
error_reporting(E_ALL);
ini_set('display_errors',1);
while on a live site, all errors have to be logged, but never shown to the client. For this, configure PHP this way:
error_reporting(E_ALL);
ini_set('display_errors', 0);
ini_set('log_errors', 1);
Note that error_reporting should be set to E_ALL all the time.
Also note that despite the common delusion, no try-catch have to be used for the error reporting. PHP will report you PDO errors already, and in a way better form. An uncaught exception is very good for development, yet if you want to show a customized error page, still don't use try catch for this, but just set a custom error handler. In a nutshell, you don't have to treat PDO errors as something special but regard them as any other error in your code.
P.S.
Sometimes there is no error but no results either. Then it means, there is no data to match your criteria. So 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 short answer that would help you to pinpoint the matching issue, Having issue with matching rows in the database using PDO. Just follow this instruction, and the linked tutorial step by step and either have your problem solved or have an answerable question for Stack Overflow.

Some time ago I had the same problem of not seeing any error messages from mysql. After a research it turned out that the problem has got nothing to do with PHP itself, but with mysql server configuration. The default value of the variable lc_messages_dir pointed to non existing directory. After adding a line in mysqld.cnf, then restarted the mysql server, and finally I was able to see the error messages. For me the following was the right one:
lc_messages_dir=/usr/share/mysql
It is described in the mysql reference manual: https://dev.mysql.com/doc/refman/5.7/en/error-message-language.html

MySQL Query Error Validation

I running a Mysql Query to select some data, Sometimes i get a error called
mysql_fetch_assoc() expects parameter 1 to be resource, boolean given
when i executed this following code,
$result = $this->db->execute($sql);
for ($i = 0; $data[$i + 1] = mysql_fetch_assoc($result); $i++);
array_pop($data);
how do i optimize this coding to prevent any errors ?
is there anything wrong with it ? should i ignore this error ?

That means that the query is buggy, whyever, most likely because you construct it using components from sources which you do not really check enough. A buggy statement throws an error (since no result can be computed). That error is returned as false instead of a mysql result ressource. Since you do not check if the query succeeded but blindly try to retrieve details from the result, you get this second error.
So there are four things you have to invest into:
you should always check if a query succeeded at all:
enclose your query into a conditional: if (FALSE!==($result=$this->db->execute($sql))) and only retrieve from the result ressource if that condition resolves to true.
make sure you really (really!) check all input data you use to construct your query. Checking here also means to encode and escape it correctly, also see point 4. for this.
in cases like this it is important to analyze what exactly it is that is going wrong. There is little sense in guessing what might be going wrong. So in addition to checking if the query succeeded at all (1.) you should also take a look at the error message mysql throws if this is not the case. Use the method mysql_error() for this. It is well documented just as every other function too.
you should rework your code and migrate from phps old, long deprecated mysql extension to either mysqli or PDO. Both are php extensions that offer more security against constructing buggy statements. Read about "prepared statements" and "parameter binding" for this.