074a979e_09___Dynamics_AX_2009_Features__Feature
[Sr.No.] 15 [Description] SQL statements in X++ have been enhanced to bring them closer to the functionality of industry standard SQL. It includes better support for inner and outer join clauses, better group by and order by clauses, and better support or using variables as a source of data to be inserted or updated. [Feature] 
X++ SQL Enhancements
Dilip's blog on DYNAMICS AX: What’s New in Dynamics AX 2009 / Dynamics AX 2009 Features
Feature