mysqli_stmt::prepare

mysqli_stmt_prepare

(PHP 5, PHP 7, PHP 8)

mysqli_stmt::prepare -- mysqli_stmt_prepare — SQL ステートメントを実行するために準備する

説明

オブジェクト指向型

public mysqli_stmt::prepare(string $query): bool

手続き型

mysqli_stmt_prepare(mysqli_stmt $statement, string $query): bool

実行する前にSQL文を準備します。指定するクエリは、単一のSQL文でなければいけません。

SQL文のテンプレートには、ゼロ個以上のパラメータマーカ (?) を含めることができます。パラメータマーカは、プレースホルダとも呼ばれています。パラメータマーカは、ステートメントを実行する前に mysqli_stmt_bind_param() を使用してアプリケーション変数にバインドする必要があります。

注意:
サーバーの max_allowed_packet よりも長いステートメントを mysqli_stmt_prepare() に渡した場合、返ってくるエラーコードは MySQL Native Driver (mysqlnd) を使っているか MySQL Client Library (libmysqlclient) を使っているかで異なります。それぞれ、次のように振る舞います。

Linux 上の mysqlnd では、エラーコード 1153 を返します。エラーメッセージは got a packet bigger than max_allowed_packet bytes です。

Windows 上の mysqlnd では、エラーコード 2006 を返します。エラーメッセージは server has gone away です。

すべてのプラットフォームの libmysqlclient では、エラーコード 2006 を返します。エラーメッセージは server has gone away です。

パラメータ

stmt

手続き型のみ: mysqli_stmt_init() が返す mysqli_stmt オブジェクト。

query

クエリを表す文字列。単一の SQL 文で構成されている必要があります。

SQL文には、適切な位置にゼロ個以上のパラメータマーカを含めることができます。パラメータマーカは、クエスチョンマーク(?)で表します。

注意:
パラメータのマーカは、それが SQL 文の適切な位置にある場合のみ有効です。例えば INSERT 文の VALUES() リストの中 (行に登録するカラムの値を指定する) や WHERE 句でカラムのデータと比較する値などが適切な位置の例です。しかし、識別子 (テーブルやカラムの名前) には使用できません。

戻り値

成功した場合に true を、失敗した場合に false を返します。

エラー / 例外

mysqli のエラー報告 (MYSQLI_REPORT_ERROR) が有効になっており、かつ要求された操作が失敗した場合は、警告が発生します。さらに、エラー報告のモードが MYSQLI_REPORT_STRICT に設定されていた場合は、mysqli_sql_exception が代わりにスローされます。

例

例1 mysqli_stmt::prepare() の例

オブジェクト指向型

<?php

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

$city = "Amersfoort";

/* プリペアドステートメントを作成します */
$stmt = $mysqli->stmt_init();
$stmt->prepare("SELECT District FROM City WHERE Name=?");

/* マーカにパラメータをバインドします */
$stmt->bind_param("s", $city);

/* クエリを実行します */
$stmt->execute();

/* 結果変数をバインドします */
$stmt->bind_result($district);

/* 値を取得します */
$stmt->fetch();

printf("%s is in district %s\n", $city, $district);

手続き型

<?php

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

$city = "Amersfoort";

/* プリペアドステートメントを作成します */
$stmt = mysqli_stmt_init($link);
mysqli_stmt_prepare($stmt, "SELECT District FROM City WHERE Name=?");

/* マーカにパラメータをバインドします */
mysqli_stmt_bind_param($stmt, "s", $city);

/* クエリを実行します */
mysqli_stmt_execute($stmt);

/* 結果変数をバインドします */
mysqli_stmt_bind_result($stmt, $district);

/* 値を取得します */
mysqli_stmt_fetch($stmt);

printf("%s is in district %s\n", $city, $district);

上の例の出力は以下となります。

Amersfoort is in district Utrecht

参考

mysqli_stmt_init() - ステートメントを初期化し、mysqli_stmt_prepare で使用するオブジェクトを返す
mysqli_stmt_execute() - プリペアドステートメントを実行する
mysqli_stmt_fetch() - プリペアドステートメントから結果を取得し、バインド変数に格納する
mysqli_stmt_bind_param() - プリペアドステートメントのパラメータに変数をバインドする
mysqli_stmt_bind_result() - 結果を保存するため、プリペアドステートメントに変数をバインドする
mysqli_stmt_get_result() - プリペアドステートメントから結果を mysqli_result オブジェクトとして取得する
mysqli_stmt_close() - プリペアドステートメントを閉じる

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User Contributed Notes 9 notes

down

logos-php at kith dot org ¶

12 years ago

Note that if you're using a question mark as a placeholder for a string value, you don't surround it with quotation marks in the MySQL query.

For example, do this:

mysqli_stmt_prepare($stmt, "SELECT * FROM foo WHERE foo.Date > ?");

Do not do this:

mysqli_stmt_prepare($stmt, "SELECT * FROM foo WHERE foo.Date > '?'");

If you put quotation marks around a question mark in the query, then PHP doesn't recognize the question mark as a placeholder, and then when you try to use mysqli_stmt_bind_param(), it gives an error to the effect that you have the wrong number of parameters.

The lack of quotation marks around a string placeholder is implicit in the official example on this page, but it's not explicitly stated in the docs, and I had trouble figuring it out, so figured it was worth posting.

down

logos-php at kith dot orgpp ¶

12 years ago

Turns out you can't directly use a prepared statement for a query that has a placeholder in an IN() clause.

There are ways around that (such as constructing a string that consists of n question marks separated by commas, then using that set of placeholders in the IN() clause), but you can't just say IN (?).

This is a MySQL restriction rather than a PHP restriction, but it's not really documented in the MySQL docs either, so I figured it was worth mentioning here.

(Btw, turns out someone else had previously posted the info that I put in my previous comment, about not using quotation marks. Sorry for the repeat; not sure how I missed the earlier comment.)

down

ndungi at gmail dot com ¶

15 years ago

The `prepare` , `bind_param`, `bind_result`, `fetch` result, `close` stmt cycle can be tedious at times. Here is an object that does all the mysqli mumbo jumbo for you when all you want is a select leaving you to the bare essential `preparedSelect` on a prepared stmt. The method returns the result set as a 2D associative array with the `select`ed columns as keys. I havent done sufficient error-checking and it also may have some bugs. Help debug and improve on it. 

I used the bible.sql db from http://www.biblesql.net/sites/biblesql.net/files/bible.mysql.gz.

Baraka tele!

============================

<?php

class DB
{
    public $connection;
    
    #establish db connection
    public function __construct($host="localhost", $user="user", $pass="", $db="bible")
    {
        $this->connection = new mysqli($host, $user, $pass, $db);
                  
        if(mysqli_connect_errno())
        {
            echo("Database connect Error : " 
            . mysqli_connect_error($mysqli));
        }    
    }
    
    #store mysqli object
    public function connect()
    {
        return $this->connection;
    }

    #run a prepared query
    public function runPreparedQuery($query, $params_r)
    {
        $stmt = $this->connection->prepare($query);
        $this->bindParameters($stmt, $params_r);

        if ($stmt->execute()) {
            return $stmt;
        } else {
            echo("Error in $statement: " 
                      . mysqli_error($this->connection));
            return 0;
        }
        
    }

 # To run a select statement with bound parameters and bound results. 
 # Returns an associative array two dimensional array which u can easily  
 # manipulate with array functions.
 
    public function preparedSelect($query, $bind_params_r)
    {
        $select = $this->runPreparedQuery($query, $bind_params_r);
        $fields_r = $this->fetchFields($select);
        
        foreach ($fields_r as $field) {
            $bind_result_r[] = &${$field};
        } 
        
        $this->bindResult($select, $bind_result_r);
        
        $result_r = array();
        $i = 0;
        while ($select->fetch()) {
            foreach ($fields_r as $field) {
                $result_r[$i][$field] = $$field;
            }
            $i++;
        }
        $select->close();
        return $result_r;    
    }
    
    
    #takes in array of bind parameters and binds them to result of 
    #executed prepared stmt
    
    private function bindParameters(&$obj, &$bind_params_r)
    {
        call_user_func_array(array($obj, "bind_param"), $bind_params_r);
    }
    
    private function bindResult(&$obj, &$bind_result_r)
    {
        call_user_func_array(array($obj, "bind_result"), $bind_result_r);
    }
    
    #returns a list of the selected field names
    
    private function fetchFields($selectStmt)
    {
        $metadata = $selectStmt->result_metadata();
        $fields_r = array();
        while ($field = $metadata->fetch_field()) {
            $fields_r[] = $field->name;
        }

        return $fields_r;
    }
}
#end of class
 
#An example of the DB class in use

$DB = new DB("localhost", "root", "", "bible");
$var = 5; 
$query = "SELECT abbr, name from books where id > ?" ;
$bound_params_r = array("i", $var);

$result_r = $DB->preparedSelect($query, $bound_params_r);

#loop thru result array and display result

foreach ($result_r as $result) {
    echo $result['abbr'] . " : " . $result['name'] . "<br/>" ;
}

?>

down

andrey at php dot net ¶

19 years ago

If you select LOBs use the following order of execution or you risk mysqli allocating more memory that actually used



1)prepare()

2)execute()

3)store_result()

4)bind_result()



If you skip 3) or exchange 3) and 4) then mysqli will allocate memory for the maximal length of the column which is 255 for tinyblob, 64k for blob(still ok), 16MByte for MEDIUMBLOB - quite a lot and 4G for LONGBLOB (good if you have so much memory). Queries which use this order a bit slower when there is a LOB but this is the price of not having memory exhaustion in seconds.

down

kontakt at arthur minus schiwon dot de ¶

16 years ago

If you wrap the placeholders with quotation marks you will experience warnings like "Number of variables doesn't match number of parameters in prepared statement" (at least with INSERT Statements).

down

mhradek AT gmail.com ¶

16 years ago

A particularly helpful adaptation of this function and the call_user_func_array function:

// $params is sent as array($val=>'i', $val=>'d', etc...)

function db_stmt_bind_params($stmt, $params)
{ 
    $funcArg[] = $stmt; 
    foreach($params as $val=>$type)
    { 
        $funcArg['type'] .= $type; 
        $funcArg[] = $val; 
    } 
    return call_user_func_array('mysqli_stmt_bind_param', $funcArgs); 
} 

Thanks to 'sned' for the code.

down

st dot john dot johnson at gmail dot com ¶

17 years ago

In reference to what lachlan76 said before, stored procedures CAN be executed through prepared statements as long as you tell the DB to move to the next result before executing again.



Example (Five calls to a stored procedure):



<?php

for ($i=0;$i<5;$i++) {

  $statement = $mysqli->stmt_init();

  $statement->prepare("CALL some_procedure( ? )");



  // Bind, execute, and bind.

  $statement->bind_param("i", 1);

  $statement->execute();

  $statement->bind_result($results);



  while($statement->fetch()) {

    // Do what you want with your results.

  }



  $statement->close();



  // Now move the mysqli connection to a new result.

  while($mysqli->next_result()) { }

}

?>



If you include the last statement, this code should execute without the nasty "Commands out of sync" error.

down

-1

lukaszNOSPAMPLEASE at epas dot pl ¶

16 years ago

i've got some bad news for you guys if you haven't found out already.

the trick with mysqli_next_result() only prevents having the connection dropped after a stored procedure call.

apparently you can bind parameters for a prepared stored procedure call, but you'll get messed up records from mysqli_stmt_fetch() after mysqli_stmt_bind_result(), at least when the stored procedure itself contains a prepared statement.

a way to avoid data corruption could be specifying the CLIENT_MULTI_STATEMENTS flag in mysqli_real_connect(), if it wasn't disabled entirely (for security reasons, as they say). another option is to use mysqli_multi_query(), but then you can't bind at all.

down

-1

lachlan76 at gmail dot com ¶

18 years ago

Do not try to use a stored procedure through a prepared statement.



Example:



<?php

$statement = $mysqli->stmt_init();

$statement->prepare("CALL some_procedure()");

?>



If you attempt to do this, it will fail by dropping the connection during the next query.  Use mysqli_multi_query instead.



Example:



<?php

$mysqli->multi_query("CALL some_procedure()");

do

{

  $result = $mysqli->store_result();



   // Do your processing work here  

  

  $result->free();

} while($mysqli->next_result());

?>



This means that you cannot bind parameters or results, however.

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