I do not understand what you mean by alter/modify database into read_only but:
You can create users that have only data read permission (with db_datareader role)
step1: create a login
create login parasdoshicom with password=’Passw0rd’
go
step 2: create user
create user parasdoshicom from login parasdoshicom
go
step 3: assign role to user
EXEC sp_addrolemember N’db_datareader’,N’parasdoshicom’
go
More details:
http://parasdoshi.com/2011/11/04/how-to-create-users-with-limited-access-in-sql-azure/
http://msdn.microsoft.com/en-us/library/ee336235.aspx
Paras Doshi (Blog: ParasDoshi.com | Twitter:
@Paras_Doshi )