Hi:
For a history of SQL from theory to implementation, see this site:
http://en.wikipedia.org/wiki/SQL
For information about how SAS conforms or deviates from the ANSI standard for SQL, see this web page:
http://support.sas.com/documentation/cdl/en/proc/59565/HTML/default/a002473705.htm (quote below is the first section from the page)
PROC SQL follows most of the guidelines set by the American National Standards Institute (ANSI) in its implementation of SQL. However, it is not fully compliant with the current ANSI Standard for SQL.(footnote 1)
The SQL research project at SAS has focused primarily on the expressive power of SQL as a query language. Consequently, some of the database features of SQL have not yet been implemented in PROC SQL.
cynthia
