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SET NAMES utf8 in MySQL?

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北海茫月
北海茫月 2020-11-22 11:30

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 pr

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  • 闹比i
    2020-11-22 11:44

    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.

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  • 一生所求
    2020-11-22 11:54

    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.
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  • 被撕碎了的回忆
    2020-11-22 11:56

    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.)

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  • 终归单人心
    2020-11-22 11:56

    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!

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  • 执笔经年
    2020-11-22 11:57

    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>
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  • 遥遥无期
    2020-11-22 11:57

    The solution is 

     $conn->set_charset("utf8");
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