# Newbie question: issue on creating blob field on mysql 5.x for windows

**URL:** <https://www.ruby-forum.com/t/newbie-question-issue-on-creating-blob-field-on-mysql-5-x-for-windows/121832>\
**Category:** Rails\
**Created:** [December 1, 2007, 5:09pm UTC](https://www.ruby-forum.com/t/newbie-question-issue-on-creating-blob-field-on-mysql-5-x-for-windows/121832 "2007-12-01T17:09:37Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![goodwill](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/ac8455/32.png) [@goodwill](https://www.ruby-forum.com/u/goodwill)\
**Post date:** [December 1, 2007, 5:09pm UTC](https://www.ruby-forum.com/t/newbie-question-issue-on-creating-blob-field-on-mysql-5-x-for-windows/121832/1 "2007-12-01T17:09:37Z")

</div>

I tried to do a migration task as follows:  
lass CreateAttachmentBlob \< ActiveRecord::Migration  
def self.up

add\_column :posts, :attachment\_thumbnail , :binary, :null=\>true,  
:limit=\>0.5.megabyte  
end

def self.down  
remove\_column :posts, :attachment\_thumbnail  
end  
end

when I do rake migrate, the following error occurred:  
Mysql::Error: #42000You have an error in your SQL syntax; check the  
manual that  
corresponds to your MySQL server version for the right syntax to use  
near ‘52428  
8.0)’ at line 1: ALTER TABLE posts ADD `attachment_thumbnail`  
blob(524288.0)

Anyone can tell me what happened? I am using rails 1.2.6 now on ruby  
1.8.6 and mysql 5.0.45 GPL.