more on userguide

docs/dc-userguide.md

@@ -4,11 +4,30 @@
 
 The Data Controller for SAS allows user to add, modify data. All changes are staged and approved before being applied to the target table. The review process, as well as using generic and repeatable code to perform updates, helps to ensure data integrity.
 
-#What is a Target Table?
+## What is a Target Table?
 A Target Table is a physical table, such as a SAS dataset or a Table in a database. The attributes of this table (eg Primary Key, loadtype, library, SCD variables etc) will have been predefined by your administrator so that you can change the data in that table safely and easily.
 
+## Why do I need the Data Controller?
+
+Alternatives to using the Data Controller for performing data updates include:
+
+1 - Writing SAS or SQL code yourself to perform data updates
+2 - Asking your DBA to to perform updates (following a change mangement process)
+3 - Saving CSVs / data on a shared-visibility network drive and building / running jobs to perform uploads in batch
+4 - Opening (and therefore locking) datasets in Enterprise Guide or SAS® Table Viewer to perform direct updates
+5 - Building a custom web application yourself to perform secure updates
+
+Problems with the above approaches include one or more of the following:
+
+ - Risk of manual error / data corruption
+ - Breaches due to unnecessary parties having access to the data
+ - Inability to trace who made the change, when, and why
+ - Reliance on key individuals to perform updates
+ - Requirement to build load routines every time a new data source is added
+ - Upload routines have to be manually modified when the table changes
+ - Legacy 'black box' solutions with little to no testing, documentation or support
+
+The Data Controller for SAS® solves the issues above.
 
 
 
-q
-