text: --cast character string columns to DATETIME(L)TZ types, in alter statement, alter_table_change_type_strict=yes
  
  autocommit off;
  drop table if exists tz_test;
  
  create table tz_test(id int, a char(40), b varchar(40), c string, d enum('a', 'b', 'c'), e enum('12:00:01.999 PM 01/02/2019', '12:00:01.999 PM 01/02/2019 +08:00', '12:00:01.999 PM 01/02/2019 +09:00', '12:00:01.999 PM 01/02/2019 Asia/Tokyo'));
  insert into tz_test values(1, 'aaa', 'bbb', 'ccc', 3, 2);
  insert into tz_test values(2, '2020-12-1 20:00:00.999', '2020-12-1 20:00:00.999', '2020-12-1 20:00:00.999', 3, 1);
  insert into tz_test values(3, '2020-12-1 20:00:00.999 +9:00', '2020-12-1 20:00:00.999 +9:00', '2020-12-1 20:00:00.999 +9:00', 2, 3);
  insert into tz_test values(4, '2020-12-1 20:00:00.999 Asia/Tokyo', '2020-12-1 20:00:00.999 Asia/Tokyo', '2020-12-1 20:00:00.999 Asia/Tokyo', 1, 4);
  insert into tz_test values(5, '2020-12-1 20:00:00.999 Asia/Tokyo', '2020-12-1 20:00:00.999 Asia/Tokyo', '2020-12-1 20:00:00.999 Asia/Tokyo', 1, 4);
  commit;
  
  set system parameters 'alter_table_change_type_strict=yes';
  set timezone 'Africa/Conakry';
  -- 0:00
  
  
  --test: cast character string columns to DATETIME types
  alter table tz_test modify a datetime;
  alter table tz_test modify b datetime;
  alter table tz_test modify c datetime;
  alter table tz_test modify d datetime;
  alter table tz_test modify e datetime;
  show full columns in tz_test;
  select * from tz_test order by 1;
  rollback;
  
  --test: cast character string columns to DATETIMELTZ types
  alter table tz_test modify a datetime with local time zone;
  alter table tz_test modify b datetime with local time zone;
  alter table tz_test modify c datetime with local time zone;
  alter table tz_test modify d datetime with local time zone;
  alter table tz_test modify e datetime with local time zone;
  show full columns in tz_test;
  select * from tz_test order by 1;
  rollback;
  
  --test: cast character string columns to DATETIMETZ types
  alter table tz_test modify a datetime with time zone;
  alter table tz_test modify b datetime with time zone;
  alter table tz_test modify c datetime with time zone;
  alter table tz_test modify d datetime with time zone;
  alter table tz_test modify e datetime with time zone;
  show full columns in tz_test;
  select * from tz_test order by 1;
  
  
  drop table tz_test;
  commit;
  
  set timezone 'Asia/Seoul';
  set system parameters 'alter_table_change_type_strict=no';
  
  autocommit on;
  