if not exists (select * from master.dbo.syslogins where loginname = N'SomeUser')
BEGIN
	declare @logindb nvarchar(132), @loginlang nvarchar(132) select @logindb = N'master', @loginlang = N'us_english'
	if @logindb is null or not exists (select * from master.dbo.sysdatabases where name = @logindb)
		select @logindb = N'master'
	if @loginlang is null or (not exists (select * from master.dbo.syslanguages where name = @loginlang) and @loginlang <> N'us_english')
		select @loginlang = @@language
	exec sp_addlogin N'SomeUser', 'somepassword', @logindb, @loginlang
END
GO

if not exists (select * from dbo.sysusers where name = N'SomeUser' and uid < 16382)
	EXEC sp_grantdbaccess N'SomeUser', N'SomeUser'
GO

if not exists (select * from dbo.sysusers where name = N'SomeRole' and uid > 16399)
	EXEC sp_addrole N'SomeRole'
GO

EXEC sp_addrolemember N'SomeRole', N'SomeUser'
GO

GRANT SELECT ON SomeTable TO SomeRole
GRANT EXECUTE ON SomeProcedure TO SomeRole