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    mysqli::real_escape_string

    mysqli_real_escape_string

    (PHP 5, PHP 7, PHP 8)

    mysqli::real_escape_string -- mysqli_real_escape_string — 接続の現在の文字セットを考慮して、SQL 文で使用する文字列の特殊文字をエスケープする

    説明

    オブジェクト指向型

    public mysqli::real_escape_string(string $string): string

    手続き型

    mysqli_real_escape_string(mysqli $mysql, string $string): string

    この関数を使用して、SQL 文中で使用できる正当な形式の SQL 文字列を作成します。 文字列 escapestr が、エスケープされた SQL に変換されます。その際、接続で使用している現在の文字セットが考慮されます。

    警告

    セキュリティ: デフォルトの文字セット

    サーバーレベルで設定するなり API 関数 mysqli_set_charset() を使うなりして、 文字セットを明示しておく必要があります。この文字セットが mysqli_real_escape_string() に影響を及ぼします。詳細は 文字セットの概念 を参照ください。

    パラメータ

    link

    手続き型のみ: mysqli_connect() あるいは mysqli_init() が返す mysqliオブジェクト。

    string

    エスケープする文字列。

    エンコードされる文字は NUL (ASCII 0)、 \n、\r、 \、'、 "、および CTRL+Z です。

    戻り値

    エスケープ済みの文字列を返します。

    例

    例1 mysqli::real_escape_string() 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 = "'s-Hertogenbosch";

    /* $city はエスケープされ、クエリは動作します。*/
    $query = sprintf("SELECT CountryCode FROM City WHERE name='%s'",
    $mysqli->real_escape_string($city));
    $result = $mysqli->query($query);
    printf("Select returned %d rows.\n", $result->num_rows);

    /* このクエリは失敗します。なぜなら、$city をエスケープしていないからです */
    $query = sprintf("SELECT CountryCode FROM City WHERE name='%s'", $city);
    $result = $mysqli->query($query);

    手続き型

    <?php

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

    $city = "'s-Hertogenbosch";

    /* $city はエスケープされ、クエリは動作します。*/
    $query = sprintf("SELECT CountryCode FROM City WHERE name='%s'",
    mysqli_real_escape_string($mysqli, $city));
    $result = mysqli_query($mysqli, $query);
    printf("Select returned %d rows.\n", mysqli_num_rows($result));

    /* このクエリは失敗します。なぜなら、$city をエスケープしていないからです */
    $query = sprintf("SELECT CountryCode FROM City WHERE name='%s'", $city);
    $result = mysqli_query($mysqli, $query);

    上の例の出力は、 たとえば以下のようになります。

    Select returned 1 rows.

Fatal error: Uncaught mysqli_sql_exception: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 's-Hertogenbosch'' at line 1 in...

    参考

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    User Contributed Notes 6 notes

    up
    60
    dave at mausner.us
    13 years ago
    You can avoid all character escaping issues (on the PHP side) if you use prepare() and bind_param(), as an alternative to placing arbitrary string values in SQL statements. This works because bound parameter values are NOT passed via the SQL statement syntax.
    up
    52
    Josef Toman
    14 years ago
    For percent sign and underscore I use this:
    <?php
    $more_escaped     = addcslashes($escaped, '%_');
    ?>
    up
    39
    arnoud at procurios dot nl
    20 years ago
    Note that this function will NOT escape _ (underscore) and % (percent) signs, which have special meanings in LIKE clauses.

    As far as I know there is no function to do this, so you have to escape them yourself by adding a backslash in front of them.
    up
    22
    therselman at gmail dot com
    7 years ago
    Presenting several UTF-8 / Multibyte-aware escape functions.

    These functions represent alternatives to mysqli::real_escape_string, as long as your DB connection and Multibyte extension are using the same character set (UTF-8), they will produce the same results by escaping the same characters as mysqli::real_escape_string.

    This is based on research I did for my SQL Query Builder class:
    https://github.com/twister-php/sql

    <?php
    /**
    * Returns a string with backslashes before characters that need to be escaped.
    * As required by MySQL and suitable for multi-byte character sets
    * Characters encoded are NUL (ASCII 0), \n, \r, \, ', ", and ctrl-Z.
    *
    * @param string $string String to add slashes to
    * @return $string with `\` prepended to reserved characters
    *
    * @author Trevor Herselman
    */
    if (function_exists('mb_ereg_replace'))
    {
    function     mb_escape(string $string)
    {
    return     mb_ereg_replace('[\x00\x0A\x0D\x1A\x22\x27\x5C]', '\\\0', $string);
    }
    } else {
    function     mb_escape(string $string)
    {
    return     preg_replace('~[\x00\x0A\x0D\x1A\x22\x27\x5C]~u', '\\\$0', $string);
    }
    }

    ?>

    Characters escaped are (the same as mysqli::real_escape_string):

    00 = \0 (NUL)
    0A = \n
    0D = \r
    1A = ctl-Z
    22 = "
    27 = '
    5C = \

    Note: preg_replace() is in PCRE_UTF8 (UTF-8) mode (`u`).

    Enhanced version:

    When escaping strings for `LIKE` syntax, remember that you also need to escape the special characters _ and %

    So this is a more fail-safe version (even when compared to mysqli::real_escape_string, because % characters in user input can cause unexpected results and even security violations via SQL injection in LIKE statements):

    <?php

    /**
    * Returns a string with backslashes before characters that need to be escaped.
    * As required by MySQL and suitable for multi-byte character sets
    * Characters encoded are NUL (ASCII 0), \n, \r, \, ', ", and ctrl-Z.
    * In addition, the special control characters % and _ are also escaped,
    * suitable for all statements, but especially suitable for `LIKE`.
    *
    * @param string $string String to add slashes to
    * @return $string with `\` prepended to reserved characters
    *
    * @author Trevor Herselman
    */
    if (function_exists('mb_ereg_replace'))
    {
    function     mb_escape(string $string)
    {
    return     mb_ereg_replace('[\x00\x0A\x0D\x1A\x22\x25\x27\x5C\x5F]', '\\\0', $string);
    }
    } else {
    function     mb_escape(string $string)
    {
    return     preg_replace('~[\x00\x0A\x0D\x1A\x22\x25\x27\x5C\x5F]~u', '\\\$0', $string);
    }
    }

    ?>

    Additional characters escaped:

    25 = %
    5F = _

    Bonus function:

    The original MySQL `utf8` character-set (for tables and fields) only supports 3-byte sequences.
    4-byte characters are not common, but I've had queries fail to execute on 4-byte UTF-8 characters, so you should be using `utf8mb4` wherever possible.

    However, if you still want to use `utf8`, you can use the following function to replace all 4-byte sequences.

    <?php
    // Modified from: https://stackoverflow.com/a/24672780/2726557
    function mysql_utf8_sanitizer(string $str)
    {
    return     preg_replace('/[\x{10000}-\x{10FFFF}]/u', "\xEF\xBF\xBD", $str);
    }
    ?>

    Pick your poison and use at your own risk!
    up
    16
    Anonymous
    9 years ago
    If you wonder why (besides \, ' and ") NUL (ASCII 0), \n, \r, and Control-Z are escaped: it is not to prevent sql injection, but to prevent your sql logfile to get unreadable.
    up
    4
    ASchmidt at Anamera dot net
    3 years ago
    Caution when escaping the % and _ wildcard characters. According to an often overlooked note at the bottom of:

    https://dev.mysql.com/doc/refman/5.7/en/string-literals.html#character-escape-sequences

    the escape sequences \% and \_ will ONLY be interpreted as % and _, *if* they occur in a LIKE! (Same for MySQL 8.0)

    In regular string literals, the escape sequences \% and \_ are treated as those two character pairs. So if those escape sequences appear in a WHERE "=" instead of a WHERE LIKE, they would NOT match a single % or _ character!

    Consequently, one MUST use two "escape" functions: The real-escape-string (or equivalent) for regular string literals, and an amended escape function JUST for string literals that are intended to be used in LIKE.
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