> > > Then I get help and this code: > > > INSERT INTO SchoolYearTeachingDays > > > SELECT aDate FROM TeachingSaturdaysInSchoolYear T WHERE T.aDate > NOT > > > IN (SELECT S.aDate FROM SchoolYearTeachingDays S) > > > > This says "insert all dates that aren't already present", which of course > avoids UNIQUE constraint. > > Just do not understand what are the 'T' and 'S' means out there, after > FROM clause. > Are they CTEs? Are they virtual tables? >
They are aliases for the table names. Another way of writing this is SELECT aDate FROM TeachingSaturdaysInSchoolYear AS T WHERE T.aDate The AS is optional, but makes it slightly clearer that you are saying use the table TeachingSaturdaysInSchoolYear and call it T. In this case it is a way of saving typing. Regards Andy Ling --------------------------------------------------------------------------------------- This email has been scanned for email related threats and delivered safely by Mimecast. For more information please visit http://www.mimecast.com --------------------------------------------------------------------------------------- _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
