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Base de données, Tables, Vues, Index et syntaxe SQL
Titre:
VFP8 GROUP BY Restriction
I imagine this question has been discussed before. If so, could you point me to earlier threads or papers?
In VFP8, for queries with a GROUP BY clause,we can no longer select columns that are not in the GROUP BY clause. This is reasonable since we can't guarrantee that those non-GROUP BY columns are the same in every row that contains the same GROUP BY column values.
However, let's assume that the developer does know that the non-GROUP BY columns are identical and only wants one row per distinct GROUP BY value. For example, a cursor contains a key value and some other value which is known to be the same for idential key values. Is there any way to extract a cursor like we used to do:
SELECT KeyValue,NonKeyValue FROM MyTable GROUP BY 1
I can figure out how to do it using xbase commands using logic like this:
1. get list of unique key values
2. create empty cursor MyResultCursor consisting of 2 columns: key value, non key value
3. scan the list of unique key values
for each key value, get the non key value from the original datar and create a row in MyResult Cursor
Somehow it seems there must be a way using just SQL to do this, but I can't figure it out. Any ideas? Thanks
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