mysql alter table add column utf8

Question

Have anybody ideas, how to add a column:

alter table tname add column cname text character set utf8 collate utf8_general_ci if not exists;

that gives an error:

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server version for the right syntax to use near 'if not exists' at line 1

I need add new column with utf-8 encoding.

Thanks

Answer 1

这不是ALTER TABLE尝试的有效语法，

alter table tname add column cname text character set utf8 collate utf8_general_ci;

Answer 2

在为表格指定排序规则时，您一直小心该表格。

alter table table_name add column column_name text character set utf8 COLLATE utf8_unicode_ci DEFAULT NULL comment 'Comment to the attachment file';