124

I often see something similar to this below in PHP scripts using MySQL

query("SET NAMES utf8");   

I have never had to do this for any project yet so I have a couple basic questions about it.

  1. Is this something that is done with PDO only?
  2. If it is not a PDO specific thing, then what is the purpose of doing it? I realize it is setting the encoding for mysql but I mean, I have never had to use it so why would I want to use it?
3
  • 4
    "SET NAMES utf8" should be avoided because of SQL injection. See php.net/manual/en/mysqlinfo.concepts.charset.php for details. Jun 8, 2013 at 11:51
  • 3
    @masakielastic I do not see where setting 'set names utf8' is a threat to sql injection? Using proper MySQL API where is the thread?
    – broadband
    Aug 29, 2013 at 7:20
  • 3
    Sorry for my unkindness. See ircmaxell's answer: stackoverflow.com/a/12118602/531320 Althogh "SET NAMES" has no problem as long as using UTF-8, the possibility you will use GBK or Big5 (Chinese) or Shift_JIS (Japanese) in the future is undeniable. Aug 29, 2013 at 8:02

8 Answers 8

78

It is needed whenever you want to send data to the server having characters that cannot be represented in pure ASCII, like 'ñ' or 'ö'.

That if the MySQL instance is not configured to expect UTF-8 encoding by default from client connections (many are, depending on your location and platform.)

Read http://www.joelonsoftware.com/articles/Unicode.html in case you aren't aware how Unicode works.

Read Whether to use "SET NAMES" to see SET NAMES alternatives and what exactly is it about.

5
  • 3
    'ö' and 'ñ' are extended ASCII. Would you still need to SET NAMES UTF8 for them?
    – Tim
    Jun 26, 2011 at 7:12
  • 2
    I have found that I often have to add utf8_decode($my_text); in PHP to get special UTF-8 characters to show on websites properly when the data was queried from MySQL. My tables and columns are set to UTF-8 in MySQL—so should this be necessary?
    – NexusRex
    Aug 30, 2011 at 19:15
  • 1
    @ Vinko Vrsalovic: Not necessarily... I had all my files in utf8 but my previous hoster has had the mysql charset set to latin1 and because i havent told mysql that I am sending chars in utf8 (hence set names utf8) it stored them in latin charset and all my special chars (Slovenian čšž) looked like they were overrun by a car - one more thing: when you make a search in phpmyadmin you wont find results, because a č is like Å and so on Jun 23, 2015 at 13:40
  • Note that it also specifies the character set that the server should use for sending results back to the client, thus is also needed when receiving this data, using for example a SELECT statement. Nov 20, 2015 at 20:54
  • 1
    @Tim. There's not really any such thing as "extended ASCII". There are a whole bunch of different encodings that can all be called extended ASCII (any single-byte character set where the first half is the same as ASCII, and there are loads of those).
    – TRiG
    Feb 11, 2020 at 14:33
49

From the manual:

SET NAMES indicates what character set the client will use to send SQL statements to the server.

More elaborately, (and once again, gratuitously lifted from the manual):

SET NAMES indicates what character set the client will use to send SQL statements to the server. Thus, SET NAMES 'cp1251' tells the server, “future incoming messages from this client are in character set cp1251.” It also specifies the character set that the server should use for sending results back to the client. (For example, it indicates what character set to use for column values if you use a SELECT statement.)

1
  • 7
    I love you. Just made my evening!
    – karim79
    Jul 25, 2012 at 20:48
38

Getting encoding right is really tricky - there are too many layers:

  • Browser
  • Page
  • PHP
  • MySQL

The SQL command "SET CHARSET utf8" from PHP will ensure that the client side (PHP) will get the data in utf8, no matter how they are stored in the database. Of course, they need to be stored correctly first.

DDL definition vs. real data

Encoding defined for a table/column doesn't really mean that the data are in that encoding. If you happened to have a table defined as utf8 but stored as differtent encoding, then MySQL will treat them as utf8 and you're in trouble. Which means you have to fix this first.

What to check

You need to check in what encoding the data flow at each layer.

  • Check HTTP headers, headers.
  • Check what's really sent in body of the request.
  • Don't forget that MySQL has encoding almost everywhere:
    • Database
    • Tables
    • Columns
    • Server as a whole
    • Client
      Make sure that there's the right one everywhere.

Conversion

If you receive data in e.g. windows-1250, and want to store in utf-8, then use this SQL before storing:

SET NAMES 'cp1250';

If you have data in DB as windows-1250 and want to retreive utf8, use:

SET CHARSET 'utf8';

Few more notes:

  • Don't rely on too "smart" tools to show the data. E.g. phpMyAdmin does (was doing when I was using it) encoding really bad. And it goes through all the layers so it's hard to find out.
  • Also, Internet Explorer had really stupid behavior of "guessing" the encoding based on weird rules.
  • Use simple editors where you can switch encoding. I recommend MySQL Workbench.
20

This query should be written before the query which create or update data in the database, this query looks like :

mysql_query("set names 'utf8'");

Note that you should write the encode which you are using in the header for example if you are using utf-8 you add it like this in the header or it will couse a problem with Internet Explorer

so your page looks like this

<html>
    <head>
        <title>page title</title>
        <meta charset="UTF-8" />   
    </head>
    <body>
    <?php
            mysql_query("set names 'utf8'");   
            $sql = "INSERT * FROM ..... ";  
            mysql_query($sql);
    ?>    

    </body>
</html>
3
  • 9
    You should not be using the PHP mysql library instead you should be using MySQLi or PDO. Nov 16, 2012 at 12:41
  • Great answer, thanks for the example. This is the one answer that helped me visualize what I needed to do and it solved my problem!
    – GTS Joe
    Jun 7, 2019 at 14:26
  • 1
    The last tag should be </html> not <html>
    – GTS Joe
    Jun 7, 2019 at 16:29
12

The solution is

 $conn->set_charset("utf8");
6

Instead of doing this via an SQL query use the php function: mysqli::set_charset mysqli_set_charset

Note:

This is the preferred way to change the charset. Using mysqli_query() to set it (such as SET NAMES utf8) is not recommended.

See the MySQL character set concepts section for more information.

from http://www.php.net/manual/en/mysqli.set-charset.php

1

Thanks @all!

don't use: query("SET NAMES utf8"); this is setup stuff and not a query. put it right afte a connection start with setCharset() (or similar method)

some little thing in parctice:

status:

  • mysql server by default talks latin1
  • your hole app is in utf8
  • connection is made without any extra (so: latin1) (no SET NAMES utf8 ..., no set_charset() method/function)

Store and read data is no problem as long mysql can handle the characters. if you look in the db you will already see there is crap in it (e.g.using phpmyadmin).

until now this is not a problem! (wrong but works often (in europe)) ..

..unless another client/programm or a changed library, which works correct, will read/save data. then you are in big trouble!

0

Not only PDO. If sql answer like '????' symbols, preset of you charset (hope UTF-8) really recommended:

if (!$mysqli->set_charset("utf8")) 
 { printf("Can't set utf8: %s\n", $mysqli->error); }

or via procedure style mysqli_set_charset($db,"utf8")

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.