What to do if php reads mysql garbled characters

Solution to php reading garbled characters from MySQL: 1. Specify the character set of the database table when creating the database table; 2. Set the character set of MySQL; 3. Set the default character encoding used when transmitting characters between databases; 4. , Set the character set used by the html page; 5. Set the character set used by the php text file.

The operating environment of this article: Windows7 system, PHP7.1 version, DELL G3 computer

Summary of the problem of php reading mysql garbled characters

When php reads mysql, the following places involve character sets.

1. Specify the character set of the database table when creating the database table. For example

1 create table tablename 
2 ( 
3 id int not null auto_increment, 
4 title varchar(20) not null,  
5 primary key ('id') 
6 )DEFAULT CHARSET =UTF8;

If the character set of the table is not specified when creating the table, the default character set of the database to which the table belongs is used. The character set is specified by character_set_database.

The method to check the character set used by the database table is:

show create table mytable;

(PS: When establishing the database/table and performing database operations, try to explicitly point out the character set used instead of relying on The default setting of MySQL, otherwise it may cause a lot of trouble when upgrading MySQL [1])

2. Mysql character set

There are three important variables in mysql, character_set_client, character_set_results, character_set_connection .

By setting character_set_client, tell Mysql what encoding method PHP stores in the database.

By setting character_set_results, tell Mysql what kind of encoded data PHP needs to get.

By setting character_set_connection, tell Mysql what encoding to use for the text in the PHP query.

3. After connecting to the database, set the default character encoding used when transmitting characters between databases.

Use mysqli::set_charset() or mysqli::query('set names utf8') to set.

Try to use mysqli::set_charset(mysqli:set_charset) instead of "SET NAMES" (refer to this article)

$db = new mysqli('localhost','user','passwd','database_name');
$db->set_charset('utf8');

Note that it is utf8, not utf-8

(A problem here is that the database and PHP have unified the encoding, but if the mysqli::set_charset() function is not called, garbled characters will still appear when reading the data. Why is this?)

（另，set names utf8相当于下面三句
SET character_set_client = utf8;
SET character_set_results = utf8; 
SET character_set_connection = utf8; 
）

4. The character set used by the html page. Set

5 in the meta tag. The character set used by the php text file.

You can use vim to open the file under Linux, enter

:set encoding

to view the character set used by the file

To ensure that it is not garbled, you need to ensure that the file itself is encoded, specified in HTML Encoding, PHP tells Mysql's encoding (including character_set_client and character_set_results) to be unified. Also use the mysqli:set_charset() function or "SET NAMES".

In response to the question after "3", I wrote several examples to test the results of setting and not setting the character set after linking to the database. Test environment Ubuntu 12.04, MySQL 5.5, php 5.5.7.

The results are as follows:

(1) The character set of the database table is utf8. Without using set names utf8

, Chinese can be inserted and read normally, but garbled characters are displayed in mysql.

(2) The database table character set is utf8. Using set names utf8

can insert and read Chinese normally, and the mysql display is correct

(3) Database table characters The set is not utf8. Use set names utf8

to display it in mysql, and all the words will be read as question marks.

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