On Fri, 4 Dec 2015 14:29:47 +0100, Even Rouault wrote:
So it looks very much like "x = NULL" is not "normal" SQL at all.
just a may be useful comment about this topic accordingly to SQL standard syntax rules NULL should never be confused with any other ordinary value; it's instead a special marker denoting the absolute _absence_ of any value. and consistently with this convention, any SQL operation or comparison including a NULL term _should_ always return a NULL result. so an expression like "x = NULL" in pure SQL terms is just a meaningless nonsense, because it will always evaluate to a NULL constant. the unique possible mechanism supported by standard SQL allowing to check for NULL values is by using the special comparison operators "x IS NULL" or "x IS NOT NULL" bye Sandro _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
