mysqli_stmt::get_result()

(PHP 5 >= 5.3.0, PHP 7)

Gets a result set from a prepared statement

说明

面向对象风格
mysqli_stmt::get_result(void): mysqli_result

过程化风格
mysqli_stmt_get_result(mysqli_stmt$stmt): mysqli_result

Call to return a result set from a prepared statement query.

参数

$stmt

仅以过程化样式：由mysqli_stmt_init()返回的 statement 标识。

返回值

Returns a resultset for successful SELECT queries, or FALSE for other DML queries or on failure. The mysqli_errno() function can be used to distinguish between the two types of failure.

仅 MySQL 原生驱动

仅可用于mysqlnd。

范例

Example #1 面向对象风格

<?php 
$mysqli = new mysqli("127.0.0.1", "user", "password", "world"); 
if($mysqli->connect_error)
{
    die("$mysqli->connect_errno: $mysqli->connect_error");
}
$query = "SELECT Name, Population, Continent FROM Country WHERE Continent=? ORDER BY Name LIMIT 1";
$stmt = $mysqli->stmt_init();
if(!$stmt->prepare($query))
{
    print "Failed to prepare statement\n";
}
else
{
    $stmt->bind_param("s", $continent);
    $continent_array = array('Europe','Africa','Asia','North America');
    foreach($continent_array as $continent)
    {
        $stmt->execute();
        $result = $stmt->get_result();
        while ($row = $result->fetch_array(MYSQLI_NUM))
        {
            foreach ($row as $r)
            {
                print "$r ";
            }
            print "\n";
        }
    }
}
$stmt->close();
$mysqli->close();
?>

Example #2 过程化风格

<?php 
$link = mysqli_connect("127.0.0.1", "user", "password", "world"); 
if (!$link)
{
    $error = mysqli_connect_error();
    $errno = mysqli_connect_errno();
    print "$errno: $error\n";
    exit();
}
$query = "SELECT Name, Population, Continent FROM Country WHERE Continent=? ORDER BY Name LIMIT 1";
$stmt = mysqli_stmt_init($link);
if(!mysqli_stmt_prepare($stmt, $query))
{
    print "Failed to prepare statement\n";
}
else
{
    mysqli_stmt_bind_param($stmt, "s", $continent);
    $continent_array = array('Europe','Africa','Asia','North America');
    foreach($continent_array as $continent)
    {
        mysqli_stmt_execute($stmt);
        $result = mysqli_stmt_get_result($stmt);
        while ($row = mysqli_fetch_array($result, MYSQLI_NUM))
        {
            foreach ($row as $r)
            {
                print "$r ";
            }
            print "\n";
        }
    }
}
mysqli_stmt_close($stmt);
mysqli_close($link);
?>

以上例程会输出：

Albania 3401200 Europe 
Algeria 31471000 Africa 
Afghanistan 22720000 Asia 
Anguilla 8000 North America 

参见

• mysqli_prepare() 准备执行一个 SQL 语句
• mysqli_stmt_result_metadata() Returns result set metadata from a prepared statement
• mysqli_stmt_fetch() Fetch results from a prepared statement into the bound variables
• mysqli_fetch_array() Fetch a result row as an associative, a numeric array, or both
• mysqli_stmt_store_result() Transfers a result set from a prepared statement
• mysqli_errno() 返回最近函数调用的错误代码

I went through a lot of trouble on a server where mysqlnd wasn't available, and had a lot of headaches.
If you don't have mysqlnd installed/loaded whatever, you will get an undefined reference when trying to call "mysqli_stmt_get_result()".
I wrote my own mysqli_stmt_get_result() and a mysqli_result_fetch_array() to go with it.
<?php
class iimysqli_result
{
  public $stmt, $nCols;
}  
function iimysqli_stmt_get_result($stmt)
{
  /**  EXPLANATION:
   * We are creating a fake "result" structure to enable us to have
   * source-level equivalent syntax to a query executed via
   * mysqli_query().
   *
   *  $stmt = mysqli_prepare($conn, "");
   *  mysqli_bind_param($stmt, "types", ...);
   *
   *  $param1 = 0;
   *  $param2 = 'foo';
   *  $param3 = 'bar';
   *  mysqli_execute($stmt);
   *  $result _mysqli_stmt_get_result($stmt);
   *    [ $arr = _mysqli_result_fetch_array($result);
   *      || $assoc = _mysqli_result_fetch_assoc($result); ]
   *  mysqli_stmt_close($stmt);
   *  mysqli_close($conn);
   *
   * At the source level, there is no difference between this and mysqlnd.
   **/
  $metadata = mysqli_stmt_result_metadata($stmt);
  $ret = new iimysqli_result;
  if (!$ret) return NULL;
  $ret->nCols = mysqli_num_fields($metadata);
  $ret->stmt = $stmt;
  mysqli_free_result($metadata);
  return $ret;
}
function iimysqli_result_fetch_array(&$result)
{
  $ret = array();
  $code = "return mysqli_stmt_bind_result(\$result->stmt ";
  for ($i=0; $i<$result->nCols; $i++)
  {
    $ret[$i] = NULL;
    $code .= ", \$ret['" .$i ."']";
  };
  $code .= ");";
  if (!eval($code)) { return NULL; };
  // This should advance the "$stmt" cursor.
  if (!mysqli_stmt_fetch($result->stmt)) { return NULL; };
  // Return the array we built.
  return $ret;
}
?>
Hope this helps someone.

Please OH PLEASE.
I have been trying to get a result set from this function, and I had 0 luck completely, for nearly 3 hours!
If you ARE using mysqli_stmt_get_results() to get a result set, in conjuction with mysqli_stmt_store_results in order to retrieve the number of rows returned, you are going to have some major trouble!
PHP Documentation states that to retrieve the number of rows returned by a prepared select sql statement, one should call the following statements respectively:
mysqli_stmt_execute($stmt);
mysqli_stmt_store_result($stmt);
$num_rows = mysqli_stmt_num_rows($stmt);
THIS IS A MAJOR DEATH TRAP, IF YOU ARE USING mysqli_stmt_get_result() in conjunction!!!! Results of doing so vary depending which statements you call first, but in the end, you will NOT get the desired result.
In conclusion, please, PLEASE, NEVER use mysqli_stmt_store_result(), then mysqli_ AND mysqli_stmt_get_result() at the the same time. This is a MAJOR death trap.
SOLUTION:
If you are trying to get a result set, and you need the number of rows returned at the same time, use the following statements respectively instead:
$result_set = mysqli_stmt_get_results($stmt);
$num_rows = mysqli_num_rows($result_set);
Reflecting on my actions, this solution may seem fairly obvious. However, to someone new using PHP (like me) or someone who is not fully comfortable with prepared statements, it's very easy to get lost by using Google and learn on your own.
Summary:
NEVER use mysqli_stmt_store_result($stmt) & mysqli_stmt_num_rows($stmt) in conjunction with mysqli_stmt_get_result($stmt). You will regret it!! I have been stuck on this for hours, and Google offered me no answer!

Please note that this method requires the mysqlnd driver. Othervise you will get this error: Call to undefined method mysqli_stmt::get_result()

For those interested, this function seems to always produce a stored result, making it equivalent to mysqli::store_result(), rather than fetching on demand as in the case of mysqli::use_result().
This is important as it means that you cannot control the nature of the result as you would normally by calling mysqli_stmt::store_result() prior to fetching, as I had personally expected.
So, if you want to emulate the behaviour of mysqli::use_result() you will still need to use mysqli_stmt::bind_param() and mysqli_stmt::fetch().

The description of get_result() indicates that it will return a resultset on success of a SELECT statement or false (boolean) in case of any other query. 
This is not true. In fact, there are cases in which get_result() will return true (boolean) e.g. when a DELETE command has been successfully send to the database. I can reproduce this case with the following code:
DELETE command send from garbage collector in a custom sessionhandler:
<?php
public function _gc($life) {
  $sessionlife = strtotime("-".SESSION_TIMEOUT."minutes");
  $dummy = "DELETE FROM sessions WHERE lastupdated< ?";
  $valueArray = array();
  $valueArray[] = $sessionlife;
  $result = $this->DB->prepQuery($dummy,$valueArray);
  return $result;
}
?>
Part of the prepQuery function to send prepared statements to the database:
<?php
$sqlquery->execute();
$result = $sqlquery->get_result(); 
$sqlqueryError = $sqlquery->errno; 
$sqlqueryAffRows = $sqlquery->affected_rows;
$sqlquery->close();
//Catch non-SELECT statements, false cases
if($result === false) {
  if($sqlqueryError == false) {
   if($sqlqueryAffRows == 0) {
     return false;
   }
   return true;
  }
  else {
   return false;
  }
}
return $this->makeArrayResult($result);
?>
that should have catched all the false (boolean) cases, and the makeArrayResult function, that only works with objects:
<?php
private function makeArrayResult($resultobj) {
  if($resultobj->num_rows == 0) { 
   return array();
  }
  else {
   $array = array();
   while($line = $resultobj->fetch_array(MYSQLI_ASSOC)) {
     array_push($array,$line);
   }
   return $array;
  }
}
?>
but which was giving me the following Error Notice:
PHP Notice -- Trying to get property of non-object
Hence the case true (boolean) needs to be considered and the description should get updated.

To prevent others from hours of screaming trying to figure out why this does not work when you have the native driver enabled. It is because you need to make sure you enable both native drives mysqlnd and nd_mysqli on your server if you wish to use this functionality.
Otherwise just enabling the mysqlnd native driver does include the mysqli_stmt_get_result function as this apparently resides in the nd_mysqli native driver. Unfortunately, most documentation only ever talks about the mysqlnd native driver.
Once you enable both native drivers this function works as documented.

Thanks to everyone that leaves notes, without them I would not be able to do what I do. I wrote this function with help from notes on this page and others.
I did not have mysqlnd available to me, but wanted to be able to get_result() of a query as an object.
PLEASE NOTE: I am not an expert at PHP
Heres an example of using my get_result() to login users
<?php
  //Sanitize input before using this function
  function login($email, $password){
    require 'connect_db.php';
    $query = $sql->stmt_init();
    if($query->prepare("SELECT CustomerId, Password, Admin FROM users WHERE Email = ?")){
      $query->bind_param("s",$email);
      $result = get_result($query); //USING FUNCTION HERE
      if($result != NULL){
        $user = $result[0];
        if(password_verify($password, $user->Password)){
          $_SESSION['user_id'] = $user->CustomerId;
          if($user->Admin == 1){
            $_SESSION['admin'] = true;
          }
          $sql->close();
          return true;
        }
      }
    }
    $sql->close();
    //If we get here they are not logged in
    return false;
  }
  //Returns an array with each row as an object
  function get_result($stmt){
    $stmt->execute(); //Execute query
    $stmt->store_result(); //Store the results
    $num_rows = $stmt->num_rows; //Get the number of results
    $results = NULL;
    if($num_rows > 0){
      //Get metadata about the results
      $meta = $stmt->result_metadata();
      //Here we get all the column/field names and create the binding code
      $bind_code = "return mysqli_stmt_bind_result(\$stmt, ";
      while($_field = $meta->fetch_field()){
        $bind_code .= "\$row[\"".$_field->name."\"], ";
      }
      //Replace trailing ", " with ");"
      $bind_code = substr_replace($bind_code,");", -2);
      //Run the code, if it doesn't work return NULL
      if(!eval($bind_code)) { 
        $stmt->close(); 
        return NULL;
      }
      //This is where we create the object and add it to our final result array
      for($i=0;$i<$num_rows;$i++){
        //Gets the row by index
        $stmt->data_seek($i);
        //Update bound variables used in $bind_code with new row values
        $stmt->fetch();
        foreach($row as $key=>$value){
          //Create array using the column/field name as the index
          $_result[$key] = $value;
        }
        //Cast $_result to object and append to our final results
        $results[$i] = (object)$_result;
      }
    }
    $stmt->close(); 
    return $results;
  }
?>