I will be creating a new blog but wants to retain my old database in my previous blo.g Can I clone the old database? If so, can you tell me steps for this? I don't want to create another because this will be a big task.
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I would suggest that you will just two ways to do it:
I saw this thread which is really helpful for the issue: http://www.techyv.com/questions/how-clone-wordpress-blog
It's not clear what you exactly want here. Do you want to clone the blog or the Database? Also if you are moving from an older version to a newer version, what I suggest is to use the WordPress auto-update tool; but before that make a backup of your files and database.
If you are creating another blog, and want to populate it with the old blog data then you might be interested in the WordPress Export tool which will export your blog posts into an XML files, that can be imported by another WordPress blog.