<< Does anyone have an idea as to how R:Base decides which rows get deleted using this command? Is it first in, last out, based on time stamp or something? Or do I use an ORDER BY to sort it out? >>
When using DELETE DUPLICATES without the USING clause the records are _exactly_ identical, so it doesn't matter which one stays and which go. When using USING R:Base will make it's own decision about which to keep. I imagine this will _usually_ be the first record in natural table order but I wouldn't count on it. If the data is different in some columns and the record you want to keep is important, I would do your own delete. You can do this with something like DELETE FROM MyTable MT1 WHERE NOT EXISTS (SELECT * FROM MyTable MT2 WHERE MT2.CaseNo = MT1.CaseNo AND MT2.CaseDate < MT1.CaseDate) This is will keep the "most recent" record (by CaseDate) for each CaseNo. Assuming CaseNo is indexed, it will be quite fast. The only problem is that if you have two CaseNo records for the SAME CaseDate, they'll both be kept. You can modify this idea to suit your particular circumstances. -- Larry
