mysql alter table add column utf8

Question

有任何想法，如何添加列：

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

這給出了一個錯誤：

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

我需要使用utf-8編碼添加新列。

謝謝

Answer 1

這不是ALTER TABLE嘗試的有效語法，

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

Answer 2

在為表格指定排序規則時，您一直小心該表格。

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