utf8mb4兼容utf8,且比utf8能表示更多的字符。
看unicode編碼區:從1~126就屬於傳統utf8區,當然utf8mb4也兼容這個區,126行以下就是utf8mb4擴充區,什麼時候你需要存儲那些字符,你才用utf8mb4,否則只是浪費空間。
MySQL 要存儲emoji表情,因此發現我們常用的utf8 字符集根本無法存儲表情。
首先將我們數據庫默認字符集由utf8 更改爲utf8mb4,對應的表默認字符集也更改爲utf8mb4 已經存儲表情的字段默認字符集也做了相應的調整。
SQL 語句
# 修改數據庫:
ALTER DATABASE database_name CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;
# 修改表:
ALTER TABLE table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
# 修改表字段:
ALTER TABLE table_name CHANGE column_name column_name VARCHAR(191) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
修改MySQL配置文件
新增如下參數:
[client]
default-character-set = utf8mb4
[mysql]
default-character-set = utf8mb4
[mysqld]
character-set-client-handshake = FALSE
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci
init_connect='SET NAMES utf8mb4'
檢查環境變量 和測試 SQL 如下:
mysql> SHOW VARIABLES WHERE Variable_name LIKE 'character\_set\_%' OR Variable_name LIKE 'collation%';
+--------------------------+--------------------+
| Variable_name | Value |
+--------------------------+--------------------+
| character_set_client | utf8mb4 |
| character_set_connection | utf8mb4 |
| character_set_database | utf8mb4 |
| character_set_filesystem | binary |
| character_set_results | utf8mb4 |
| character_set_server | utf8mb4 |
| character_set_system | utf8 |
| collation_connection | utf8mb4_unicode_ci |
| collation_database | utf8mb4_unicode_ci |
| collation_server | utf8mb4_unicode_ci |
+--------------------------+--------------------+
rows in set (0.00 sec)
MySQL版本必須爲5.5.3以上版本,否則不支持字符集utf8mb4。
原文地址:https://www.cnblogs.com/guoziyi/p/6054112.html
參考地址:https://dev.mysql.com/doc/refman/5.7/en/charset-unicode-utf8mb4.html