SQL Server - How to Grant Read Access to ALL databases to a Login?

Question

I need to give a new login read access to all 300 databases on a server. How can I accomplish this without checking 300 checkboxes in the user mapping area?

Answer 1

I had to tweak Martin Smith's answer slightly as:

1. The spaces and linebreaks resulted in not all the text being generated properly
2. The QUOTENAME in the Exec statement put in square brackets which is incorrect.

My version:

SET NOCOUNT ON;

DECLARE @user_name    SYSNAME
        , @login_name SYSNAME;

SELECT @user_name = 'HelpdeskUser',
       @login_name = 'Helpdesk'

SELECT 'USE ' + QUOTENAME(NAME) + ';
        CREATE USER ' + QUOTENAME(@user_name)
       + ' FOR LOGIN ' + QUOTENAME(@login_name)
       + ' WITH DEFAULT_SCHEMA=[dbo];
    EXEC sys.sp_addrolemember ''db_datareader'',''' + @user_name + ''';
    EXEC sys.sp_addrolemember ''db_denydatawriter'', ''' + @user_name + '''; 
GO'
FROM   sys.databases
WHERE  database_id > 4
       AND state_desc = 'ONLINE' 

Otherwise works perfectly. Thanks