mysqli::query

mysqli_query

(PHP 5, PHP 7, PHP 8)

mysqli::query -- mysqli_query — Performs a query on the database

Descrizione

Stile orientato agli oggetti

public mysqli::query(string $query, int $result_mode = MYSQLI_STORE_RESULT): mysqli_result|bool

Stile procedurale

mysqli_query(mysqli $mysql, string $query, int $result_mode = MYSQLI_STORE_RESULT): mysqli_result|bool

Performs a query against the database.

Avviso

Security warning: SQL injection

If the query contains any variable input then parameterized prepared statements should be used instead. Alternatively, the data must be properly formatted and all strings must be escaped using the mysqli_real_escape_string() function.

For non-DML queries (not INSERT, UPDATE or DELETE), this function is similar to calling mysqli_real_query() followed by either mysqli_use_result() or mysqli_store_result().

Nota:
In the case where a statement is passed to mysqli_query() that is longer than max_allowed_packet of the server, the returned error codes are different depending on whether you are using MySQL Native Driver (mysqlnd) or MySQL Client Library (libmysqlclient). The behavior is as follows:

mysqlnd on Linux returns an error code of 1153. The error message means got a packet bigger than max_allowed_packet bytes.

mysqlnd on Windows returns an error code 2006. This error message means server has gone away.

libmysqlclient on all platforms returns an error code 2006. This error message means server has gone away.

Elenco dei parametri

link

Solo nello stile procedurale: un identificatore restituito da mysqli_connect() o mysqli_init()

query

The query string.

result_mode

The result mode can be one of 3 constants indicating how the result will be returned from the MySQL server.

MYSQLI_STORE_RESULT (default) - returns a mysqli_result object with buffered result set.

MYSQLI_USE_RESULT - returns a mysqli_result object with unbuffered result set. As long as there are pending records waiting to be fetched, the connection line will be busy and all subsequent calls will return error Commands out of sync. To avoid the error all records must be fetched from the server or the result set must be discarded by calling mysqli_free_result().

MYSQLI_ASYNC (available with mysqlnd) - the query is performed asynchronously and no result set is immediately returned. mysqli_poll() is then used to get results from such queries. Used in combination with either MYSQLI_STORE_RESULT or MYSQLI_USE_RESULT constant.

Valori restituiti

Returns false on failure. For successful queries which produce a result set, such as SELECT, SHOW, DESCRIBE or EXPLAIN, mysqli_query() will return a mysqli_result object. For other successful queries, mysqli_query() will return true.

Errori/Eccezioni

If mysqli error reporting is enabled (MYSQLI_REPORT_ERROR) and the requested operation fails, a warning is generated. If, in addition, the mode is set to MYSQLI_REPORT_STRICT, a mysqli_sql_exception is thrown instead.

Esempi

Example #1 mysqli::query() example

Stile orientato agli oggetti

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");

/* Create table doesn't return a resultset */
$mysqli->query("CREATE TEMPORARY TABLE myCity LIKE City");
printf("Table myCity successfully created.\n");

/* Select queries return a resultset */
$result = $mysqli->query("SELECT Name FROM City LIMIT 10");
printf("Select returned %d rows.\n", $result->num_rows);

/* If we have to retrieve large amount of data we use MYSQLI_USE_RESULT */
$result = $mysqli->query("SELECT * FROM City", MYSQLI_USE_RESULT);

/* Note, that we can't execute any functions which interact with the
    server until all records have been fully retrieved or the result
    set was closed. All calls will return an 'out of sync' error */
$mysqli->query("SET @a:='this will not work'");

Stile procedurale

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$link = mysqli_connect("localhost", "my_user", "my_password", "world");

/* Create table doesn't return a resultset */
mysqli_query($link, "CREATE TEMPORARY TABLE myCity LIKE City");
printf("Table myCity successfully created.\n");

/* Select queries return a resultset */
$result = mysqli_query($link, "SELECT Name FROM City LIMIT 10");
printf("Select returned %d rows.\n", mysqli_num_rows($result));

/* If we have to retrieve large amount of data we use MYSQLI_USE_RESULT */
$result = mysqli_query($link, "SELECT * FROM City", MYSQLI_USE_RESULT);

/* Note, that we can't execute any functions which interact with the
    server until all records have been fully retrieved or the result
    set was closed. All calls will return an 'out of sync' error */
mysqli_query($link, "SET @a:='this will not work'");

The above examples will output something similar to:

Table myCity successfully created.
Select returned 10 rows.

Fatal error: Uncaught mysqli_sql_exception: Commands out of sync; you can't run this command now in...

Vedere anche:

mysqli_execute_query() - Prepares, binds parameters, and executes SQL statement
mysqli_real_query() - Execute an SQL query
mysqli_multi_query() - Performs one or more queries on the database
mysqli_prepare() - Prepares an SQL statement for execution
mysqli_free_result() - Frees the memory associated with a result

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User Contributed Notes 8 notes

down

NUNTIUS ¶

16 years ago

This may or may not be obvious to people but perhaps it will help someone.



When running joins in SQL you may encounter a problem if you are trying to pull two columns with the same name. mysqli returns the last in the query when called by name. So to get what you need you can use an alias.



Below I am trying to join a user id with a user role. in the first table (tbl_usr), role is a number and in the second is a  text name (tbl_memrole is a lookup table). If I call them both as role I get the text as it is the last "role" in the query. If I use an alias then I get both as desired as shown below.



<?php

$sql = "SELECT a.uid, a.role AS roleid, b.role, 

            FROM tbl_usr a

            INNER JOIN tbl_memrole b

            ON a.role = b.id

            ";



    if ($result = $mysqli->query($sql)) {

        while($obj = $result->fetch_object()){

            $line.=$obj->uid;

            $line.=$obj->role;

            $line.=$obj->roleid;

        }

    }

    $result->close();

    unset($obj);

    unset($sql);

    unset($query);

    

?>

In this situation I guess I could have just renamed the role column in the first table roleid and that would have taken care of it, but it was a learning experience.

down

theyranos at gmail dot com ¶

13 years ago

The cryptic "Couldn't fetch mysqli" error message can mean any number of things, including:

1. You're trying to use a database object that you've already closed (as noted by ceo at l-i-e dot com). Reopen your database connection, or find the call to <?php mysqli_close($db); ?> or <?php $db->close(); ?> and remove it.
2. Your MySQLi object has been serialized and unserialized for some reason. Define a wakeup function to re-create your database connection. http://php.net/__wakeup 
3. Something besides you closed your mysqli connection (in particular, see http://bugs.php.net/bug.php?id=33772)
4. You mixed OOP and functional calls to the database object. (So, you have <?php $db->query() ?> in the same program as <?php mysqli_query($db) ?>).

down

petrus.jvr ¶

13 years ago

When calling multiple stored procedures, you can run into the following error: "Commands out of sync; you can't run this command now".
This can happen even when using the close() function on the result object between calls. 
To fix the problem, remember to call the next_result() function on the mysqli object after each stored procedure call. See example below:

<?php
// New Connection
$db = new mysqli('localhost','user','pass','database');

// Check for errors
if(mysqli_connect_errno()){
 echo mysqli_connect_error();
}

// 1st Query
$result = $db->query("call getUsers()");
if($result){
     // Cycle through results
    while ($row = $result->fetch_object()){
        $user_arr[] = $row;
    }
    // Free result set
    $result->close();
    $db->next_result();
}

// 2nd Query
$result = $db->query("call getGroups()");
if($result){
     // Cycle through results
    while ($row = $result->fetch_object()){
        $group_arr[] = $row;
    }
     // Free result set
     $result->close();
     $db->next_result();
}
else echo($db->error);

// Close connection
$db->close();
?>

down

xa at sagexa dot com ¶

2 years ago

"In PHP 8.1, the default error handling behavior of the MySQLi extension has changed from silencing errors to throw an Exception on errors. "
This is true even for the procedural use of mysqli, i.e. mysqli_query.
Hence, using if(!mysqli_query($c, $sql)) [...] is pointless.
To disable Exception throwing : mysqli_report(MYSQLI_REPORT_OFF);

down

Anonymous ¶

6 years ago

Here is an example of a clean query into a html table

<table>
   <tr>
     <th>First Name</th>
     <th>Last Name</th>
     <th>City</th>
   </tr>
   <?php while ($row = $myquery->fetch_assoc()) { ?>
   <tr>
     <td><?php echo $row["firstname"]; ?></td>
     <td><?php echo $row["lastname"]; ?></td>
     <td><?php echo $row["city"];?></td>
   </tr>
   <?php } ?>
 </table>

down

Beeners ¶

18 years ago

Stored Procedures.

Use mysqli_query to call a stored procedure that returns a result set. 

Here is a short example:

<?php
$mysqli = new mysqli(DBURI,DBUSER,DBPASS,DBNAME);
if (mysqli_connect_errno()) 
{
  printf("Connection failed: %s\n", mysqli_connect_error());
  exit();
}

$SQL = "CALL my_procedure($something)";
if ( ($result = $mysqli->query($SQL))===false )
{
  printf("Invalid query: %s\nWhole query: %s\n", $mysqli->error, $SQL);
  exit();
}

while ($myrow = $result->fetch_array(MYSQLI_ASSOC))
{
  $aValue[]=$myrow["a"];
  $bValue[]=$myrow["b"];
}
$result->close();
$mysqli->close();
?>
I hope this saves someone some time.

down

-1

registrations at jdfoxmicro dot com ¶

14 years ago

I like to save the query itself in a log file, so that I don't have to worry about whether the site is live.



For example, I might have a global function:



<?php

function UpdateLog ( $string , $logfile )  {

   $fh = fopen ( $logfile , 'a' );

   $fwrite ( $fh , strftime ('%F %T %z')." ".$string."\n";

   fclose ( $fh );

}

?>



Then in my mysql function error trapper, something like this:



<?php

   $error_msg = "Database error in [page].php / ";

   $error_msg .= mysqli_error ( $link )." / ";

   $error_msg .= $query;

   UpdateLog ( $error_msg , DB_ERROR_LOG_FILE );

?>



I also include the remote IP, user agent, etc., but I left it out of these code samples.  And have it e-mail me when an error is caught, too.



Jeff

down

-1

ceo at l-i-e dot com ¶

16 years ago

Translation:
"Couldn't fetch mysqli"

You closed your connection and are trying to use it again.

It has taken me DAYS to figure out what this obscure error message means...

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