Subject Re: FALSE or <> or not From rouke <moc.liamg@rekkabrg> Date Wed, 30 Dec 2020 19:05:14 -0500 Newsgroups dbase.getting-started Thanks Ken. That makes perfect sense. Happy holidays. Rouke Ken Mayer Wrote: > On 12/30/2020 1:30 PM, rouke wrote: > > In dbase plus 8 with ADO I have a simple table with a few character, date, numeric fields and a logical field. The logical field (field name 'returned') is a tick box. I have double clicked some of the tick boxes and left some as they were. The double clicked tick boxes show a tick, the other ones don't. I assume the ones that do not show a tick are .F. or .N. and the ones that do show a tick are .T. or .Y.. If I 'set filter to returned', all records with ticked tick boxes show, when I 'set filter to not returned' only those records with unticked tick boxes show. But when I 'set filter to returned = .F.', a seemingly random and much smaller number (only 3) of records show, albeit with the tick boxes unticked. When I 'set filter to returned<>.T.', all records with an unticked tick box show. So I wonder, what's the difference between FALSE or <> or not? > > By default a field is "null". The value "null" is a third state for a > logical field -- it means it wasn't touched by anyone, it is neither > true or false. (By the way, in dBASE Plus and going back to Visual dBASE > 7, if not earlier, you can stop using .t. and .f. and so on, and use the > words true and false, which are easier to read and type ...) > > If you want only the true items, then a filter for "true" is easy > enough, if you want it for ones that are not "true", just use NOT true > in the code, or as you are using it "not returned" will work. Basically > it means that no one set the value to true or false. The other solution > is to set a default value when adding a record, and setting it to false > that way. If you're using ADO, that implies you're using a back-end > server database, and you can set a default value for your logical fields > in those tables as well, you can set it to false and that would resolve > the issue. > > Ken > > -- > *Ken Mayer* > Ken's dBASE Page: http://www.goldenstag.net/dbase > The dUFLP: http://www.goldenstag.net/dbase/index.htm#duflp > dBASE Books: http://www.goldenstag.net/dbase/Books/dBASEBooks.htm > dBASE Tutorial: http://www.goldenstag.net/dbase/Tutorial/00_Preface.htm