CREATE TEMPORARY TABLE tmp_backup_tables_priv AS SELECT * FROM mysql.tables_priv;
CREATE TEMPORARY TABLE tmp_backup_user AS SELECT * FROM mysql.user;
DROP DATABASE sys;
SHOW DATABASES;
Database
information_schema
mtr
mysql
performance_schema
test
mysql.columns_priv                                 OK
mysql.db                                           OK
mysql.engine_cost                                  OK
mysql.event                                        OK
mysql.func                                         OK
mysql.general_log                                  OK
mysql.gtid_executed                                OK
mysql.help_category                                OK
mysql.help_keyword                                 OK
mysql.help_relation                                OK
mysql.help_topic                                   OK
mysql.innodb_index_stats                           OK
mysql.innodb_table_stats                           OK
mysql.ndb_binlog_index                             OK
mysql.plugin                                       OK
mysql.proc                                         OK
mysql.procs_priv                                   OK
mysql.proxies_priv                                 OK
mysql.server_cost                                  OK
mysql.servers                                      OK
mysql.slave_master_info                            OK
mysql.slave_relay_log_info                         OK
mysql.slave_worker_info                            OK
mysql.slow_log                                     OK
mysql.tables_priv                                  OK
mysql.time_zone                                    OK
mysql.time_zone_leap_second                        OK
mysql.time_zone_name                               OK
mysql.time_zone_transition                         OK
mysql.time_zone_transition_type                    OK
mysql.user                                         OK
mtr.global_suppressions                            OK
mtr.test_suppressions                              OK
sys.sys_config                                     OK
SHOW DATABASES;
Database
information_schema
mtr
mysql
performance_schema
sys
test
TRUNCATE TABLE mysql.tables_priv;
INSERT INTO mysql.tables_priv (SELECT * FROM tmp_backup_tables_priv);
DROP TEMPORARY TABLE tmp_backup_tables_priv;
TRUNCATE TABLE mysql.user;
INSERT INTO mysql.user (SELECT * FROM tmp_backup_user);
DROP TEMPORARY TABLE tmp_backup_user;
FLUSH PRIVILEGES;
