mysql alter table add column utf8

Question

有任何想法，如何添加专栏：

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

发出错误：

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编码添加新列。

由于

Answer 1

这不是ALTER TABLE的有效语法 尝试，

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

Answer 2

在将排序规则指定给表时，您对表已经非常小心了。

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