[Monetdb-developers] semantics of aggregation operations

Torsten Grust torsten.grust at gmail.com
Thu May 18 16:14:08 CEST 2006

> [...]
> A small detail of SQL spec that might be relevant:
> If a column contains only NULL or no values at all the result of the
> aggregate function is NULL.  COUNT is an exception, obviously.

Yes, I think it is relevant.  Because the semantics of SUM are as is,  
a SQL query can tell an all-NULL column (yields NULL) from an empty  
aggregation input set (yields 0).  I vote for the status quo.

   | Prof. Dr. Torsten Grust                         grust at in.tum.de |
   |                                 http://www-db.in.tum.de/~grust/ |
   |     Database Systems - Technische Universität München (Germany) |

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