Will Apple's mobile phone system upgrade delete the address book and SMS? If not, will there be other effects?

There are two ways to update the Phone 1 * * * system, one is to use WiFi directly on the mobile phone, and the other is to connect with itunes on the computer. When the phone is connected to itunes, iTunes will automatically synchronize the information once and back up the data in the phone. After the mobile phone is upgraded to ios5 with itunes, the data in the mobile phone will be erased; However, when the new ios5 firmware is installed on the itunes phone, the data backed up by the previous phone will be completely restored to the phone. So the phone records, contacts, information, etc. before and after the upgrade. It will be stored in your mobile phone intact.