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This article introduces the knowledge of "what are the MySQL character set and proofreading rules". Many people will encounter such a dilemma in the operation of actual cases, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

View all available character sets:

Mysql > show character set

+-- +

| | Charset | Description | Default collation | Maxlen | |

+-- +

| | utf8 | UTF-8 Unicode | utf8_general_ci | 3 |

View character set (character): how to save and proofread rules (collation): how to compare strings

Select * from information_schema.character_sets

Proofread rules

Mysql > show collation like'% gbk%'

+-- +

| | Collation | Charset | Id | Default | Compiled | Sortlen | |

+-- +

| | gbk_chinese_ci | gbk | 28 | Yes | Yes | 1 |

| | gbk_bin | gbk | 87 | | Yes | 1 | |

+-- +

2 rows in set (0.00 sec)

Name the setting:

Character set name begins with +:

_ ci (case insensitive)

_ cs (case sensitive)

_ bin (binary, comparison character value, insensitive to case)

Example:

Select case when 'A' COLLATE utf8_general_ci='a' collate utf8_general_ci then 1 else 0 end

one

-- the proofreading rule is that ci time is the same as An and a

Select case when 'A' COLLATE utf8_bin='a' collate utf8_bin then 1 else 0 end

0

Setting of Mysql character set

SERVER server category, DB data level, TABLE table level, field level

SERVER server character set and proofreading rules

1. My.cnf (ini) configuration

[mysql]

Character-set-server=utf8

two。 Start options

Mysqld-character-set-server=utf8

3. Specify when editing

Cmake. -DDEFAULT_CHARSET=utf8

If none of the above is specified, use: latin1

Mysql > show variables like 'character_set_server%'

+-+ +

| | Variable_name | Value |

+-+ +

| | character_set_server | utf8 |

+-+ +

1 row in set (0.00 sec)

Mysql > show variables like 'collation_server%'

+-+ +

| | Variable_name | Value |

+-+ +

| | collation_server | utf8_general_ci |

+-+ +

1 row in set (0.00 sec)

DB database character set proofreading rules

Alter database can be modified at the time of data creation, but existing data will not be modified.

1 > if DB character set and proofreading rules are specified, use the

2 > if the DB character set is specified and no proofreading is specified, use the character set default proofreading

3 > if DB proofreading is specified and no character set is specified, use proofreading related character sets

4 > if DB character set and proofing are not configured, use server character set and proofreading

Mysql > show variables like 'character_set_database%'

+-+ +

| | Variable_name | Value |

+-+ +

| | character_set_database | utf8 |

+-+ +

1 row in set (0.00 sec)

Mysql > show variables like 'collation_database%'

+-+ +

| | Variable_name | Value |

+-+ +

| | collation_database | utf8_general_ci |

+-+ +

1 row in set (0.00 sec)

Table character set and proofreading

CREATE TABLE `t` (

`id` varchar (100) DEFAULT NULL

`context` text

) ENGINE=InnoDB DEFAULT CHARSET=utf8

Specify when table is built, if the db character set is not set

Connection character set

Character_set_client client character set

Character_set_connection connection character set

Character_ser_results returns the character set

The three parameters are guaranteed to be the same, and the input and output of the guarantee are normal.

Settings:

[mysql]

Default-character-set=utf8

Can be configured uniformly:

Set names utf8

Mandatory setting character set

Select _ utf8 'character set', _ big5 'character set'

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