升級安裝5.6版本mysql

linux環境下的yum默認mysql版本是5.1的，由于項目需要保存表情等4個字節的數據，版本受限，需要升級到5.6版本支持utf8mb4格式的編碼。

升級過程大概就是備份數據庫，完全卸載舊版本，重新安裝5.6版本，原先5.1版本下的數據庫需要根據自己情況調整設置

安裝成功后，測試保存emoji表情符號

修改數據庫編碼格式

例如：

ALTER DATABASE Test CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

修改表的編碼格式

例如：

ALTER TABLE TABLE_NAME CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

?測試提交emoji表情，仍然返回不能保存這個字符

java.sql.SQLException: Incorrect string value: ‘\xF0\x9F\x92\x94’ for column ‘name’ at row 1

檢查數據庫變量

SHOW VARIABLES WHERE Variable_name LIKE 'character_set_%' OR Variable_name LIKE 'collation%'; Variable_nameValue

character_set_client	utf8
character_set_connection	utf8
character_set_database	utf8
character_set_filesystem	binary
character_set_results	utf8
character_set_server	utf8
character_set_system	utf8
collation_connection	utf8_unicode_ci
collation_database	utf8_unicode_ci
collation_server	utf8_unicode_ci

?

發現數據庫的系統變量仍然是utf8編碼格式的

以下幾個一定要設置成utf8mb4格式

系統變量描述

character_set_client	(客戶端來源數據使用的字符集)
character_set_connection	(連接層字符集)
character_set_database	(當前選中數據庫的默認字符集)
character_set_results	(查詢結果字符集)
character_set_server	(默認的內部操作字符集)

數據庫連接參數中:?
characterEncoding=utf8會被自動識別為utf8mb4，也可以不加這個參數，會自動檢測。?
而autoReconnect=true是必須加上的。

修改my.conf文件

下面的這個是mysql的配置文件，尤為重要，如果不指定啟動的編碼格式，還是會默認安裝utf8格式啟動，就算數據庫和表字段都設置成utf8mb4編碼格式依然會不能保存4個字節的數據

# For advice on how to change settings please see # http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html # *** DO NOT EDIT THIS FILE. It's a template which will be copied to the # *** default location during install, and will be replaced if you # *** upgrade to a newer version of MySQL.[mysqld]# Remove leading # and set to the amount of RAM for the most important data # cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%. # innodb_buffer_pool_size = 128M# Remove leading # to turn on a very important data integrity option: logging # changes to the binary log between backups. # log_bin# These are commonly set, remove the # and set as required. # basedir = ..... # datadir = ..... # port = ..... # server_id = ..... # socket = .....# Remove leading # to set options mainly useful for reporting servers. # The server defaults are faster for transactions and fast SELECTs. # Adjust sizes as needed, experiment to find the optimal values. # join_buffer_size = 128M # sort_buffer_size = 2M # read_rnd_buffer_size = 2M sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES [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'

?
如果你已經啟動mysql了，使用這個配置重啟服務即可

service mysqld stop// 關閉服務 service mysqld start// 開啟服務

重啟完成后我們再次查看系統變量，輸出如下

Variable_nameValue

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

?

再次測試自己的接口，保存成功

?

轉載于:https://www.cnblogs.com/MrSong97/p/10500130.html

總結

以上是生活随笔為你收集整理的Mysql升级过程的问题的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。