本篇文章給大家?guī)淼膬?nèi)容是關(guān)于mysql8.0新特性的總結(jié)（附代碼），有一定的參考價值，有需要的朋友可以參考一下，希望對你有所幫助。
1、 默認字符集由latin1變?yōu)閡tf8mb4
在8.0版本之前，默認字符集為latin1，utf8指向的是utf8mb3，8.0版本默認字符集為utf8mb4，utf8默認指向的也是utf8mb4。
（推薦：MySQL教程）
2. MyISAM系統(tǒng)表全部換成InnoDB表
系統(tǒng)表全部換成事務(wù)型的innodb表，默認的MySQL實例將不包含任何MyISAM表，除非手動創(chuàng)建MyISAM表。
# MySQL 5.7 mysql> select distinct(ENGINE) from information_schema.tables; +--------------------+ | ENGINE | +--------------------+ | MEMORY | | InnoDB | | MyISAM | | CSV | | PERFORMANCE_SCHEMA | | NULL | +--------------------+ 6 rows in set (0.00 sec) # MySQL 8.0 mysql> select distinct(ENGINE) from information_schema.tables; +--------------------+ | ENGINE | +--------------------+ | NULL | | InnoDB | | CSV | | PERFORMANCE_SCHEMA | +--------------------+ 4 rows in set (0.00 sec)
3. 自增變量持久化
在8.0之前的版本，自增主鍵AUTO_INCREMENT的值如果大于max(primary key)+1，在MySQL重啟后，會重置AUTO_INCREMENT=max(primary key)+1，這種現(xiàn)象在某些情況下會導(dǎo)致業(yè)務(wù)主鍵沖突或者其他難以發(fā)現(xiàn)的問題。自增主鍵重啟重置的問題很早就被發(fā)現(xiàn)(https://bugs.mysql.com/bug.ph…)，一直到8.0才被解決，8.0版本將會對AUTO_INCREMENT值進行持久化，MySQL重啟后，該值將不會改變。
4. DDL原子化
InnoDB表的DDL支持事務(wù)完整性，要么成功要么回滾，將DDL操作回滾日志寫入到data dictionary 數(shù)據(jù)字典表 mysql.innodb_ddl_log 中用于回滾操作，該表是隱藏的表，通過show tables無法看到。通過設(shè)置參數(shù)，可將ddl操作日志打印輸出到mysql錯誤日志中。
mysql> set global log_error_verbosity=3; mysql> set global innodb_print_ddl_logs=1; mysql> create table t1(c int) engine=innodb; # MySQL錯誤日志: 2018-06-26T11:25:25.817245+08:00 44 [Note] [MY-012473] [InnoDB] InnoDB: DDL log insert : [DDL record: DELETE SPACE, id=41, thread_id=44, space_id=6, old_file_path=./db/t1.ibd] 2018-06-26T11:25:25.817369+08:00 44 [Note] [MY-012478] [InnoDB] InnoDB: DDL log delete : by id 41 2018-06-26T11:25:25.819753+08:00 44 [Note] [MY-012477] [InnoDB] InnoDB: DDL log insert : [DDL record: REMOVE CACHE, id=42, thread_id=44, table_id=1063, new_file_path=db/t1] 2018-06-26T11:25:25.819796+08:00 44 [Note] [MY-012478] [InnoDB] InnoDB: DDL log delete : by id 42 2018-06-26T11:25:25.820556+08:00 44 [Note] [MY-012472] [InnoDB] InnoDB: DDL log insert : [DDL record: FREE, id=43, thread_id=44, space_id=6, index_id=140, page_no=4] 2018-06-26T11:25:25.820594+08:00 44 [Note] [MY-012478] [InnoDB] InnoDB: DDL log delete : by id 43 2018-06-26T11:25:25.825743+08:00 44 [Note] [MY-012485] [InnoDB] InnoDB: DDL log post ddl : begin for thread id : 44 2018-06-26T11:25:25.825784+08:00 44 [Note] [MY-012486] [InnoDB] InnoDB: DDL log post ddl : end for thread id : 44
來看另外一個例子，庫里只有一個t1表，drop table t1,t2; 試圖刪除t1,t2兩張表,在5.7中，執(zhí)行報錯，但是t1表被刪除，在8.0中執(zhí)行報錯，但是t1表沒有被刪除，證明了8.0 DDL操作的原子性，要么全部成功，要么回滾。
# MySQL 5.7 mysql> show tables; +---------------+ | Tables_in_db | +---------------+ | t1 | +---------------+ 1 row in set (0.00 sec) mysql> drop table t1, t2; ERROR 1051 (42S02): Unknown table 'db.t2' mysql> show tables; Empty set (0.00 sec) # MySQL 8.0 mysql> show tables; +---------------+ | Tables_in_db | +---------------+ | t1 | +---------------+ 1 row in set (0.00 sec) mysql> drop table t1, t2; ERROR 1051 (42S02): Unknown table 'db.t2' mysql> show tables; +---------------+ | Tables_in_db | +---------------+ | t1 | +---------------+ 1 row in set (0.00 sec)
5. 參數(shù)修改持久化
MySQL 8.0版本支持在線修改全局參數(shù)并持久化，通過加上PERSIST關(guān)鍵字，可以將修改的參數(shù)持久化到新的配置文件（mysqld-auto.cnf）中，重啟MySQL時，可以從該配置文件獲取到最新的配置參數(shù)。
例如執(zhí)行：
set PERSIST expire_logs_days=10 ;
系統(tǒng)會在數(shù)據(jù)目錄下生成一個包含json格式的 mysqld-auto.cnf 的文件，格式化后如下所示，當(dāng) my.cnf 和 mysqld-auto.cnf 同時存在時，后者具有更高優(yōu)先級。
{ "Version": 1, "mysql_server": { "expire_logs_days": { "Value": "10", "Metadata": { "Timestamp": 1529657078851627, "User": "root", "Host": "localhost" } } } }
6. 新增降序索引
MySQL在語法上很早就已經(jīng)支持降序索引，但實際上創(chuàng)建的仍然是升序索引，如下MySQL 5.7 所示，c2字段降序，但是從show create table看c2仍然是升序。8.0可以看到，c2字段降序。
# MySQL 5.7 mysql> create table t1(c1 int,c2 int,index idx_c1_c2(c1,c2 desc)); Query OK, 0 rows affected (0.03 sec) mysql> show create table t1G *************************** 1. row *************************** Table: t1 Create Table: CREATE TABLE `t1` ( `c1` int(11) DEFAULT NULL, `c2` int(11) DEFAULT NULL, KEY `idx_c1_c2` (`c1`,`c2`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 1 row in set (0.00 sec) # MySQL 8.0 mysql> create table t1(c1 int,c2 int,index idx_c1_c2(c1,c2 desc)); Query OK, 0 rows affected (0.06 sec) mysql> show create table t1G *************************** 1. row *************************** Table: t1 Create Table: CREATE TABLE `t1` ( `c1` int(11) DEFAULT NULL, `c2` int(11) DEFAULT NULL, KEY `idx_c1_c2` (`c1`,`c2` DESC) ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci ROW_FORMAT=DYNAMIC 1 row in set (0.00 sec)
再來看看降序索引在執(zhí)行計劃中的表現(xiàn)，在t1表插入10萬條隨機數(shù)據(jù)，查看select * from t1 order by c1 , c2 desc;的執(zhí)行計劃。從執(zhí)行計劃上可以看出，5.7的掃描數(shù)100113遠遠大于8.0的5行，并且使用了filesort。
DELIMITER ;; CREATE PROCEDURE test_insert () BEGIN DECLARE i INT DEFAULT 1; WHILE i<100000 DO insert into t1 select rand()*100000, rand()*100000; SET i=i+1; END WHILE ; commit; END;; DELIMITER ; CALL test_insert(); # MySQL 5.7 mysql> explain select * from t1 order by c1 , c2 desc limit 5; +----+-------------+-------+------------+-------+---------------+-----------+---------+------+--------+----------+-----------------------------+ | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+-------+------------+-------+---------------+-----------+---------+------+--------+----------+-----------------------------+ | 1 | SIMPLE | t1 | NULL | index | NULL | idx_c1_c2 | 10 | NULL | 100113 | 100.00 | Using index; Using filesort | +----+-------------+-------+------------+-------+---------------+-----------+---------+------+--------+----------+-----------------------------+ 1 row in set, 1 warning (0.00 sec) # MySQL 8.0 mysql> explain select * from t1 order by c1 , c2 desc limit 5; +----+-------------+-------+------------+-------+---------------+-----------+---------+------+------+----------+-------------+ | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+-------+------------+-------+---------------+-----------+---------+------+------+----------+-------------+ | 1 | SIMPLE | t1 | NULL | index | NULL | idx_c1_c2 | 10 | NULL | 5 | 100.00 | Using index | +----+-------------+-------+------------+-------+---------------+-----------+---------+------+------+----------+-------------+ 1 row in set, 1 warning (0.00 sec)
降序索引只是對查詢中特定的排序順序有效，如果使用不當(dāng)，反而查詢效率更低，比如上述查詢排序條件改為 order by c1 desc, c2 desc，這種情況下，5.7的執(zhí)行計劃要明顯好于8.0的，如下：
# MySQL 5.7 mysql> explain select * from t1 order by c1 desc , c2 desc limit 5; +----+-------------+-------+------------+-------+---------------+-----------+---------+------+------+----------+-------------+ | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+-------+------------+-------+---------------+-----------+---------+------+------+----------+-------------+ | 1 | SIMPLE | t1 | NULL | index | NULL | idx_c1_c2 | 10 | NULL | 5 | 100.00 | Using index | +----+-------------+-------+------------+-------+---------------+-----------+---------+------+------+----------+-------------+ 1 row in set, 1 warning (0.01 sec) # MySQL 8.0 mysql> explain select * from t1 order by c1 desc , c2 desc limit 5; +----+-------------+-------+------------+-------+---------------+-----------+---------+------+--------+----------+-----------------------------+ | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+-------+------------+-------+---------------+-----------+---------+------+--------+----------+-----------------------------+ | 1 | SIMPLE | t1 | NULL | index | NULL | idx_c1_c2 | 10 | NULL | 100429 | 100.00 | Using index; Using filesort | +----+-------------+-------+------------+-------+---------------+-----------+---------+------+--------+----------+-----------------------------+ 1 row in set, 1 warning (0.01 sec)
7. group by 不再隱式排序
mysql 8.0 對于group by 字段不再隱式排序，如需要排序，必須顯式加上order by 子句。
# 表結(jié)構(gòu) mysql> show create table tb1G *************************** 1. row *************************** Table: tb1 Create Table: CREATE TABLE `tb1` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(50) DEFAULT NULL, `group_own` int(11) DEFAULT '0', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci ROW_FORMAT=DYNAMIC 1 row in set (0.00 sec) # 表數(shù)據(jù) mysql> select * from tb1; +----+------+-----------+ | id | name | group_own | +----+------+-----------+ | 1 | 1 | 0 | | 2 | 2 | 0 | | 3 | 3 | 0 | | 4 | 4 | 0 | | 5 | 5 | 5 | | 8 | 8 | 1 | | 10 | 10 | 5 | +----+------+-----------+ 7 rows in set (0.00 sec) # MySQL 5.7 mysql> select count(id), group_own from tb1 group by group_own; +-----------+-----------+ | count(id) | group_own | +-----------+-----------+ | 4 | 0 | | 1 | 1 | | 2 | 5 | +-----------+-----------+ 3 rows in set (0.00 sec) # MySQL 8.0.11 mysql> select count(id), group_own from tb1 group by group_own; +-----------+-----------+ | count(id) | group_own | +-----------+-----------+ | 4 | 0 | | 2 | 5 | | 1 | 1 | +-----------+-----------+ 3 rows in set (0.00 sec) # MySQL 8.0.11顯式地加上order by進行排序 mysql> select count(id), group_own from tb1 group by group_own order by group_own; +-----------+-----------+ | count(id) | group_own | +-----------+-----------+ | 4 | 0 | | 1 | 1 | | 2 | 5 | +-----------+-----------+ 3 rows in set (0.00 sec)
8. JSON特性增強
MySQL 8 大幅改進了對 JSON 的支持，添加了基于路徑查詢參數(shù)從 JSON 字段中抽取數(shù)據(jù)的 JSON_EXTRACT() 函數(shù)，以及用于將數(shù)據(jù)分別組合到 JSON 數(shù)組和對象中的 JSON_ARRAYAGG() 和 JSON_OBJECTAGG() 聚合函數(shù)。
在主從復(fù)制中，新增參數(shù) binlog_row_value_options，控制JSON數(shù)據(jù)的傳輸方式，允許對于Json類型部分修改，在binlog中只記錄修改的部分，減少json大數(shù)據(jù)在只有少量修改的情況下，對資源的占用。
9. redo & undo 日志加密
增加以下兩個參數(shù)，用于控制redo、undo日志的加密。
innodb_undo_log_encrypt
innodb_undo_log_encrypt
10. innodb select for update跳過鎖等待
select … for update，select … for share(8.0新增語法) 添加 NOWAIT、SKIP LOCKED語法，跳過鎖等待，或者跳過鎖定。
在5.7及之前的版本，select…for update，如果獲取不到鎖，會一直等待，直到innodb_lock_wait_timeout超時。
在8.0版本，通過添加nowait，skip locked語法，能夠立即返回。如果查詢的行已經(jīng)加鎖，那么nowait會立即報錯返回，而skip locked也會立即返回，只是返回的結(jié)果中不包含被鎖定的行。
# session1: mysql> begin; mysql> select * from t1 where c1 = 2 for update; +------+-------+ | c1 | c2 | +------+-------+ | 2 | 60530 | | 2 | 24678 | +------+-------+ 2 rows in set (0.00 sec) # session2: mysql> select * from t1 where c1 = 2 for update nowait; ERROR 3572 (HY000): Statement aborted because lock(s) could not be acquired immediately and NOWAIT is set. mysql> select * from t1 where c1 = 2 for update skip locked; Empty set (0.00 sec)
11. 增加SET_VAR語法
在sql語法中增加SET_VAR語法，動態(tài)調(diào)整部分參數(shù)，有利于提升語句性能。
- select /+ SET_VAR(sort_buffer_size = 16M) / id ?from test order id ;
- insert ?/+ SET_VAR(foreign_key_checks=OFF) / into test(name) values(1);
12. 支持不可見索引
使用INVISIBLE關(guān)鍵字在創(chuàng)建表或者進行表變更中設(shè)置索引是否可見。索引不可見只是在查詢時優(yōu)化器不使用該索引，即使使用force index，優(yōu)化器也不會使用該索引，同時優(yōu)化器也不會報索引不存在的錯誤，因為索引仍然真實存在，在必要時，也可以快速的恢復(fù)成可見。
# 創(chuàng)建不可見索引 create table t2(c1 int,c2 int,index idx_c1_c2(c1,c2 desc) invisible ); # 索引可見 alter table t2 alter index idx_c1_c2 visible; # 索引不可見 alter table t2 alter index idx_c1_c2 invisible;
13. 支持直方圖
優(yōu)化器會利用column_statistics的數(shù)據(jù)，判斷字段的值的分布，得到更準(zhǔn)確的執(zhí)行計劃。
可以使用 ANALYZE TABLE table_name [UPDATE HISTOGRAM on col_name with N BUCKETS |DROP HISTOGRAM ON ?clo_name] 來收集或者刪除直方圖信息。
直方圖統(tǒng)計了表中某些字段的數(shù)據(jù)分布情況，為優(yōu)化選擇高效的執(zhí)行計劃提供參考，直方圖與索引有著本質(zhì)的區(qū)別，維護一個索引有代價。每一次的insert、update、delete都會需要更新索引，會對性能有一定的影響。而直方圖一次創(chuàng)建永不更新，除非明確去更新它。所以不會影響insert、update、delete的性能。
# 添加/更新直方圖 mysql> analyze table t1 update histogram on c1, c2 with 32 buckets; +--------+-----------+----------+-----------------------------------------------+ | Table | Op | Msg_type | Msg_text | +--------+-----------+----------+-----------------------------------------------+ | db.t1 | histogram | status | Histogram statistics created for column 'c1'. | | db.t1 | histogram | status | Histogram statistics created for column 'c2'. | +--------+-----------+----------+-----------------------------------------------+ 2 rows in set (2.57 sec) # 刪除直方圖 mysql> analyze table t1 drop histogram on c1, c2; +--------+-----------+----------+-----------------------------------------------+ | Table | Op | Msg_type | Msg_text | +--------+-----------+----------+-----------------------------------------------+ | db.t1 | histogram | status | Histogram statistics removed for column 'c1'. | | db.t1 | histogram | status | Histogram statistics removed for column 'c2'. | +--------+-----------+----------+-----------------------------------------------+ 2 rows in set (0.13 sec)
14. 新增innodb_dedicated_server參數(shù)
能夠讓InnoDB根據(jù)服務(wù)器上檢測到的內(nèi)存大小自動配置innodb_buffer_pool_size，innodb_log_file_size，innodb_flush_method三個參數(shù)。
15. 日志分類更詳細
在錯誤信息中添加了錯誤信息編號[MY-010311]和錯誤所屬子系統(tǒng)[Server]
# MySQL 5.7 2018-06-08T09:07:20.114585+08:00 0 [Warning] 'proxies_priv' entry '@ root@localhost' ignored in --skip-name-resolve mode. 2018-06-08T09:07:20.117848+08:00 0 [Warning] 'tables_priv' entry 'user mysql.session@localhost' ignored in --skip-name-resolve mode. 2018-06-08T09:07:20.117868+08:00 0 [Warning] 'tables_priv' entry 'sys_config mysql.sys@localhost' ignored in --skip-name-resolve mode. # MySQL 8.0 2018-06-21T17:53:13.040295+08:00 28 [Warning] [MY-010311] [Server] 'proxies_priv' entry '@ root@localhost' ignored in --skip-name-resolve mode. 2018-06-21T17:53:13.040520+08:00 28 [Warning] [MY-010330] [Server] 'tables_priv' entry 'user mysql.session@localhost' ignored in --skip-name-resolve mode. 2018-06-21T17:53:13.040542+08:00 28 [Warning] [MY-010330] [Server] 'tables_priv' entry 'sys_config mysql.sys@localhost' ignored in --skip-name-resolve mode.
16. undo空間自動回收
- innodb_undo_log_truncate參數(shù)在8.0.2版本默認值由OFF變?yōu)镺N，默認開啟undo日志表空間自動回收。
- innodb_undo_tablespaces參數(shù)在8.0.2版本默認為2，當(dāng)一個undo表空間被回收時，還有另外一個提供正常服務(wù)。
- innodb_max_undo_log_size參數(shù)定義了undo表空間回收的最大值，當(dāng)undo表空間超過這個值，該表空間被標(biāo)記為可回收。
17. 增加資源組
MySQL 8.0新增了一個資源組功能，用于調(diào)控線程優(yōu)先級以及綁定CPU核。
MySQL用戶需要有 RESOURCE_GROUP_ADMIN權(quán)限才能創(chuàng)建、修改、刪除資源組。
在Linux環(huán)境下，MySQL進程需要有 CAP_SYS_NICE 權(quán)限才能使用資源組完整功能。
[root@localhost~]# sudo setcap cap_sys_nice+ep /usr/local/mysql8.0/bin/mysqld [root@localhost~]# getcap /usr/local/mysql8.0/bin/mysqld /usr/local/mysql8.0/bin/mysqld = cap_sys_nice+ep
默認提供兩個資源組，分別是USR_default，SYS_default
創(chuàng)建資源組：
create resource group test_resouce_group type=USER vcpu=0,1 thread_priority=5;
將當(dāng)前線程加入資源組：
SET RESOURCE GROUP test_resouce_group;
將某個線程加入資源組：
SET RESOURCE GROUP test_resouce_group FOR thread_id;
查看資源組里有哪些線程：
select * from Performance_Schema.threads where RESOURCE_GROUP=’test_resouce_group’;
修改資源組：
alter resource group test_resouce_group vcpu = 2,3 THREAD_PRIORITY = 8;
刪除資源組 ：
drop resource group test_resouce_group;
# 創(chuàng)建資源組 mysql>create resource group test_resouce_group type=USER vcpu=0,1 thread_priority=5; Query OK, 0 rows affected (0.03 sec) mysql> select * from RESOURCE_GROUPS; +---------------------+---------------------+------------------------+----------+-----------------+ | RESOURCE_GROUP_NAME | RESOURCE_GROUP_TYPE | RESOURCE_GROUP_ENABLED | VCPU_IDS | THREAD_PRIORITY | +---------------------+---------------------+------------------------+----------+-----------------+ | USR_default | USER | 1 | 0-3 | 0 | | SYS_default | SYSTEM | 1 | 0-3 | 0 | | test_resouce_group | USER | 1 | 0-1 | 5 | +---------------------+---------------------+------------------------+----------+-----------------+ 3 rows in set (0.00 sec) # 把線程id為60的線程加入到資源組test_resouce_group中，線程id可通過Performance_Schema.threads獲取 mysql> SET RESOURCE GROUP test_resouce_group FOR 60; Query OK, 0 rows affected (0.00 sec) # 資源組里有線程時，刪除資源組報錯 mysql> drop resource group test_resouce_group; ERROR 3656 (HY000): Resource group test_resouce_group is busy. # 修改資源組 mysql> alter resource group test_resouce_group vcpu = 2,3 THREAD_PRIORITY = 8; Query OK, 0 rows affected (0.10 sec) mysql> select * from RESOURCE_GROUPS; +---------------------+---------------------+------------------------+----------+-----------------+ | RESOURCE_GROUP_NAME | RESOURCE_GROUP_TYPE | RESOURCE_GROUP_ENABLED | VCPU_IDS | THREAD_PRIORITY | +---------------------+---------------------+------------------------+----------+-----------------+ | USR_default | USER | 1 | 0-3 | 0 | | SYS_default | SYSTEM | 1 | 0-3 | 0 | | test_resouce_group | USER | 1 | 2-3 | 8 | +---------------------+---------------------+------------------------+----------+-----------------+ 3 rows in set (0.00 sec) # 把資源組里的線程移出到默認資源組USR_default mysql> SET RESOURCE GROUP USR_default FOR 60; Query OK, 0 rows affected (0.00 sec) # 刪除資源組 mysql> drop resource group test_resouce_group; Query OK, 0 rows affected (0.04 sec)
18. 增加角色管理
角色可以認為是一些權(quán)限的集合，為用戶賦予統(tǒng)一的角色，權(quán)限的修改直接通過角色來進行，無需為每個用戶單獨授權(quán)。
# 創(chuàng)建角色 mysql> create role role_test; Query OK, 0 rows affected (0.03 sec) # 給角色授予權(quán)限 mysql> grant select on db.* to 'role_test'; Query OK, 0 rows affected (0.10 sec) # 創(chuàng)建用戶 mysql> create user 'read_user'@'%' identified by '123456'; Query OK, 0 rows affected (0.09 sec) # 給用戶賦予角色 mysql> grant 'role_test' to 'read_user'@'%'; Query OK, 0 rows affected (0.02 sec) # 給角色role_test增加insert權(quán)限 mysql> grant insert on db.* to 'role_test'; Query OK, 0 rows affected (0.08 sec) # 給角色role_test刪除insert權(quán)限 mysql> revoke insert on db.* from 'role_test'; Query OK, 0 rows affected (0.10 sec) # 查看默認角色信息 mysql> select * from mysql.default_roles; +------+-----------+-------------------+-------------------+ | HOST | USER | DEFAULT_ROLE_HOST | DEFAULT_ROLE_USER | +------+-----------+-------------------+-------------------+ | % | read_user | % | role_test | +------+-----------+-------------------+-------------------+ 1 row in set (0.00 sec) # 查看角色與用戶關(guān)系 mysql> select * from mysql.role_edges; +-----------+-----------+---------+-----------+-------------------+ | FROM_HOST | FROM_USER | TO_HOST | TO_USER | WITH_ADMIN_OPTION | +-----------+-----------+---------+-----------+-------------------+ | % | role_test | % | read_user | N | +-----------+-----------+---------+-----------+-------------------+ 1 row in set (0.00 sec) # 刪除角色 mysql> drop role role_test; Query OK, 0 rows affected (0.06 sec)
