Ever had this error?
“Database diagram support objects cannot be installed because this database does not have a valid owner. To continue, first use the Files page of the Database Properties dialog box or the ALTER AUTHORIZATION statement to set the database owner to a valid login, than add the database diagram support objects.”

I’ve always added a user and it’s been a real hazzle to be honest. However, I now found this little nifty script you can run instead:

ALTER AUTHORIZATION ON DATABASE::DATABASENAME TO [sa];

Tada!