(PHP 5)
mysqli::query -- mysqli_query — Performs a query on the database
Object oriented style
Procedural style
   Performs a query against the database.
  
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().
Note:
In the case where you pass a statement 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".
linkProcedural style only: A link identifier returned by mysqli_connect() or mysqli_init()
queryThe query string.
Data inside the query should be properly escaped.
resultmode
       Either the constant MYSQLI_USE_RESULT or
       MYSQLI_STORE_RESULT depending on the desired
       behavior. By default, MYSQLI_STORE_RESULT is used.
      
       If you use MYSQLI_USE_RESULT all subsequent calls
       will return error Commands out of sync unless you
       call mysqli_free_result()
      
       With MYSQLI_ASYNC (available with mysqlnd), it is
       possible to perform query asynchronously.
       mysqli_poll() is then used to get results from such
       queries.
      
   Returns FALSE on failure. For successful SELECT, SHOW, DESCRIBE or
   EXPLAIN queries mysqli_query() will return
   a mysqli_result object. For other successful queries mysqli_query() will
   return TRUE.
  
| Version | Description | 
|---|---|
| 5.3.0 | Added the ability of async queries. | 
Example #1 mysqli::query() example
Object oriented style
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if ($mysqli->connect_errno) {
    printf("Connect failed: %s\n", $mysqli->connect_error);
    exit();
}
/* Create table doesn't return a resultset */
if ($mysqli->query("CREATE TEMPORARY TABLE myCity LIKE City") === TRUE) {
    printf("Table myCity successfully created.\n");
}
/* Select queries return a resultset */
if ($result = $mysqli->query("SELECT Name FROM City LIMIT 10")) {
    printf("Select returned %d rows.\n", $result->num_rows);
    /* free result set */
    $result->close();
}
/* If we have to retrieve large amount of data we use MYSQLI_USE_RESULT */
if ($result = $mysqli->query("SELECT * FROM City", MYSQLI_USE_RESULT)) {
    /* Note, that we can't execute any functions which interact with the
       server until result set was closed. All calls will return an
       'out of sync' error */
    if (!$mysqli->query("SET @a:='this will not work'")) {
        printf("Error: %s\n", $mysqli->error);
    }
    $result->close();
}
$mysqli->close();
?>
Procedural style
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}
/* Create table doesn't return a resultset */
if (mysqli_query($link, "CREATE TEMPORARY TABLE myCity LIKE City") === TRUE) {
    printf("Table myCity successfully created.\n");
}
/* Select queries return a resultset */
if ($result = mysqli_query($link, "SELECT Name FROM City LIMIT 10")) {
    printf("Select returned %d rows.\n", mysqli_num_rows($result));
    /* free result set */
    mysqli_free_result($result);
}
/* If we have to retrieve large amount of data we use MYSQLI_USE_RESULT */
if ($result = mysqli_query($link, "SELECT * FROM City", MYSQLI_USE_RESULT)) {
    /* Note, that we can't execute any functions which interact with the
       server until result set was closed. All calls will return an
       'out of sync' error */
    if (!mysqli_query($link, "SET @a:='this will not work'")) {
        printf("Error: %s\n", mysqli_error($link));
    }
    mysqli_free_result($result);
}
mysqli_close($link);
?>
The above examples will output:
Table myCity successfully created. Select returned 10 rows. Error: Commands out of sync; You can't run this command now