SQL Server roles and permissions - sql-server

Question

I really need some advice about adding roles at the server level and apply some permissions that will be applicable to each database on my server.
Basically I need to two roles read only and read write.
The read will have permissions to select and see any object
The write will have permissions to select/insert/delete and execute any object
I want to create a server role, then a login associated to this role (which can be a AD group) and after that for each database create a user that will inherits all permissions from the server role.
So on each database, I will have each user that belongs to the server role created, the problem is to clearly define the permissions, is not straight forward in my opinion.
What I can see, I cannot assign read or write to a role and then use it on each db, on the contrary on the General tab of the server role I have a bunch of permissions that is not clear which one to use for this purpose.
Maybe I'm doing it wrong but I want to have something at the server level and not define the same role on each db for that purpose. I'm using SQL server 2014.

Answer 1

The short answer is you can't.
Generally, server-level permissions are not propagated down to individual objects within databases. The only exception is a sysadmin role, which I would strongly encourage you not to use for this purpose, as you would essentially give up the control of the entire server instance to every member of it.
As a kind of a shorthand, you can use built-in database roles to save yourself a bit of trouble. For read-only access, a membership in db_datareader role is usually enough, unless you have stored procedures that return datasets which this role is supposed to be able to execute. There is also a similar role for modification, db_datawriter, but it doesn't cover the execute permission. So you will have to create a custom role for that:
create role [DataChanger] authorization [dbo];
go
alter role [db_datareader] add member [DataChanger];
go
alter role [db_datawriter] add member [DataChanger];
go
grant execute to [DataChanger];
go
-- Now you can add your members. Here is a reader
create user [Domain\MyUser1] from login [Domain\MyUser1];
go
alter role [db_datareader] add member [Domain\MyUser1];
go
-- Writer
create user [Domain\MyUser2] from login [Domain\MyUser2];
go
alter role [DataChanger] add member [Domain\MyUser2];
go
These permissions will automatically pick up newly created objects, without you having to explicitly add new permissions after every schema modification.
You will have to do this in the context of every user database that you want to manage in this way. You can probably create a SQL Agent job which will run periodically and introduce these changes in any user databases which don't have them already (for example, if a database has been restored from earlier backup, or brought from another server, or a new one was created). Also, since you can't loop through databases in static code, you will need to wrap it into a dynamic SQL and loop through sys.databases, or maybe via an undocumented sp_MSforeachdb system stored procedure. Oh, and don't forget to remove all these go statements from dynamic code, as they are not part of SQL, and are only recognised by SSMS and sqlcmd.
P.S. All that being said, I hope you are not going to manage any production databases in this manner. I don't even know where to start on how insecure this approach is.