Install database backup

After doing an automatic update on my site, my site now only shows a blank white screen. I can’t get into my site at all.
I am trying to restore my database using a backup but each time I try I get this message in php myadmin.

Error

SQL query:

# WordPress MySQL database backup
#
# Generated: Wednesday 15. February 2012 23:22 GMT
# Hostname: 172.16.5.31
# Database: db1031558_sa27097_main
# ——————————————————–
# ——————————————————–
# Table: wp_commentmeta
# ——————————————————–
#
# Delete any existing table wp_commentmeta
#
DROP TABLE IF EXISTS wp_commentmeta ;

MySQL said: Documentation
#1046 – No database selected

I have tried two different backups but get nothing from either. I followed the instructions here but keep getting the error above. My site is http://www.canadaabu.com

I would be grateful of any pointers.
Thanks a million
Susan