bharatstop on "bulk update post content."

Hi

I want to update post content. adding more text to the existing post content through phpbbyadmin sql query.

I found some queries in net, but all are just replacing the all the posts content with another text.

But I want to update post content (add more text to it) based on some conditions.

Conditions are,

Category = "Test" (all posts)
where metakey = "Video_Code" and
metakey "Value" is not empty
then
update postcontent + "<iframe width="560" height="315" src="//www.youtube.com/embed/MetaKeyValue" frameborder="0" allowfullscreen></iframe>"

any help appreciated.

Thank

[Please don't bump]