SQL statement to add a local Windows user to SQL server, and then add them to all databases as a datareader. Note: uses sp_addrolemember which is depreciated in post-2012. I haven't found a way to do this manually in < 2012 as the alter role command doesn't support adding a user.

gistfile1.txt

DECLARE @UserName sysname;
DECLARE @NameToAdd sysname;
DECLARE @S nvarchar(1000)

SET @UserName = 'User Name';
SET @NameToAdd = @@SERVERNAME + '\' + @UserName;
 
-- Create a login using windows auth
--set @s = 'CREATE LOGIN ' + quotename(@NameToAdd) + ' FROM WINDOWS;'
--exec (@S)
 
-- Add user to all databases as db_datareader
set @S = 'Use [?]; CREATE USER ' + quotename(@NameToAdd) + ' FOR LOGIN ' + quotename(@NameToAdd) + '; exec sp_addrolemember ''db_datareader'' , ' + quotename(@NameToAdd) + ';';
Exec sp_MSforeachdb @command1 = @S;