i have install joomla 1.0 but i want upgrade t0 1.5 which done by downloading the migrator and upload it to my server but am having this problem during the Pre-installation Check am getting this result "An error has occurred Could not connect to the database. Connector returned number: Unable to connect to the database pls how can i solve this problem

Interestingly, I am reading a Joomla 1.5 book, authored by Barrie North, one of the creators of Joomla 1.5, "Joomla! A user's guide: Building a successful joomla! powered website (2008)" 

You might be out of luck.  Here is what he has to say on the matter of upgrading (I will try to type as much as I can.  Where I Can't, it will be abridged such that you get the point, so bear with me please):

You can't upgrade from 1.0 to 1.5.  There are significant enough changes in the code that simply over writing files would break your site.  Joomla 1.5 doesn't provide an upgrade path from earlier versions.  Converting an older site to 1.5 requires populating the new site with the content from the old site.  This migration of content is not a 1-to-1 process and involves conversions and modifications to the content dump.

THis has been a deliberate choice to minimize the number of users who might attempt the "overwrite teh files" technique.

1.5 is so signifcantly changed from 1.0 that there is no upgrade path.  That is why we are provdidinhg the migration path.  The concept is to build a new site and to migrate data from the old site. Extensions need to be installed and configured as if the site is new.  The core data migration does reconstruct menue items for core elements and also keeps core module records with configuration settings.

As if this isn't frustrating enough, I just checked www.compassdesigns.net/ and 1.6 might be out as early as august (http://www.compassdesigns.net/joomla-blog/tags/joomla-1.6/)

Other possible solutions, based on experience:
1) Ensure that all the necessary folders are writeable in which case, atimes as you may know, tis best to go with FTP.
2) (This doesn't have to do with migration but might help nonetheless) One time, I installed joomla and had to run the install again as somethig went wrong in the process. For some reason, the 2nd time around, it didn't like the fact that I gave it the name of the db I created, even though it was the only one there and I created it specifically for joomla. I ended up having to drop the db and recreating it. Again, Joomla didn't like that so in the end, I dumped it again, created a brand new db, gave it the name of the new one and everything worked like a charm.

I hope this helps with your issue.

yawa thanks alot i followed the author of the book u are just reading said i deleted the joomla 1.0 and the database i created earlier and i then upload the 1.5 and created a new data base and bingo the installation is complete pls can you send me the book if it is an ebook i will appreciate it once thanks for your help

Feyisara,

I wish I could but it isn't an ebook and I scoured the net extensively for an ebook version to no avail, hence my buying the actual book online.  I wish you could get it.  It was a pure coincidence that you posted your question just when I had it with me and I actually typed everything in my original post (cos from your posts, you are a nice person ).

Not to rub it in but it is a damned good book and worth every penny!

Hopefully it will make it to rapidshare et al in the near future.