Hi there,
I have 2 computers,the one is for business and the other is private.I just want to sync a calendar on one computer (business) and the music on another one (private),but everytime i try to synchronise only the calendar with itunes homesharing, it deletes all my music on my iphone.Is there any way to solve this problem???
Any help will be greatly appreciated!

Just uncheck content like music, videos & apps on the computer you only want to sync your calendar with and to sync the music is the same.Moreover u can sync your calendars with multiple computers.
If it still can't work,you may refer to this article How to transfer iPhone Contacts, SMS, Calendar,Notes & Call History ,it also include transfering music.Hope it could help u.

Generally speaking, you can only sync with 1 iTunes account/computer at a time. You can easily sync calendar over the air via google calendar, or exchange, depending on what your calendar is *in* on the desktop.
I'd explore that option.To help you solve the problem, here's some instruction, hope it can help you:
PC Users: How to transfer iPhone calendar, SMS, contacts, music, videos to PC
Mac Users: How to transfer iPhone calendar, SMS, contacts, music, videos to Mac

1 make sure your iphone is the latest one .if it isn?t ,then get it updated to take advantage of the latest features.
2 open iTunes on the secondary computer and connect your iphone with it .choose cancel, when a widown pops up asking for erasing and rewriting of data.
3 select ?Manually Manage Music and Movies? option under the summary tab ,transfer music from that computer?s iTunes library to your iphone .
Once you have purchased apps, they stay purchased and you can reinstall any apps from an authorized PC, after signing in to your iTunes account. So that's how you can sync iPhone with two computers and protect your data from getting erased!
If above can?t help you , here I share a page for you how to transfer calender music from iphone computer[/URL] how to transfer calender music from iphone computer Maybe this is useful for you.
http://www.levesoft.com/how-to-transfer-music-songs-from-iPhone-to-pc.html

Well, it is very straight forward procedure. When you sync the iphone to your computer and when you click on your iphone setting in the itunes, there is option given to uncheck videos, music, apps, etc; so all you need to do is just unckeck the things that you do not want to sync in the computer and only the checked things will be synced in the computer.
For more detailed guide of sync content to iPone, follow this tip "Sync iPhone Content to the computer"
For PC:How to transfer iPhone files to computer
For Mac:How to transfer iPhone contents to Mac computer