From: Vieglais, D. A <vie...@ku...> - 2003-02-05 20:16:07
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John W. asked the question this morning of how to search for records where a concept IS NULL or even IS NOT NULL. The answer is pretty simple- the current release of DiGIR does not support this- why not is a mystery to me. So I just added this capability to the test provider on velo and will push the code to CVS today, but wanted to check with the group first about the best way to do this. The following describes the changes made thus far: A NULL comparison term is specified in the query by having a blank (i.e. zero length) string in the comparison term. This type of parameter is valid under the following conditions: 1. Concept type is TEXT, NUMERIC, or DATETIME 2. The comparison operator is "equals" or "not equals" 3. If "not equals" is specified and the term is NULL, then the value of <minQueryTermLength> for the resource is examined. If this value is zero then the query is allowed, otherwise the query fails. So basically the following is always allowed: WHERE ConceptFOO IS NULL And this is only allowed when minQueryTermLength is 0: WHERE ConceptFOO IS NOT NULL |