does Locate have a next/prev funtion
lazarus / 16-Databases

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WTDdallas · 2016-07-28 15:21

I am doing a lookup in a dataset using Locate, Work great but, There
are more that one entry that match the search.

Is there a way to do a locate.next or locate.prev ?

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Handoko · 2016-07-28 15:57

So far as I know TDBF.Locate doesn't support Next and Prev. But it can
be achieved by using TStrings. Use Locate to get the results and save
it to TString.

Other way to do it is to create your own Singly Linked List or Doubly
Linked List data structure to store the results. It's probably the
hardest way. But if you've done it, you'll be happy because you have
programmed something that is very complicated.

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Thaddy · 2016-07-28 15:57

Locate is standard - in its base functionality only - unidirectional
so subsequent locate calls (depending on locate options, maybe
increase recno by 1 in dbf) should find the next. Just try it.
If there is an index, though, locate uses the index and this scheme
won't work.

Normally you would simply write an Sql  select query, but if that is
not present?

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antelove19 · 2016-07-28 17:31

if ADOQuery1.Locate('time', timeday,[])  then
  begin
           DataModule1.ADOQuery1.MoveBy(1);
          //DataModule1.ADOQuery1.Next;
  end;

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mangakissa · 2016-08-03 06:17

dataset.MoveBy is doing the same as dataset.next

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mariodosreis · 2016-08-24 13:37

Try this:
      //It works most of the times
      mykey:= #xyz ; // Some Key
      If tdDbf1.Locate... Then
       With tdDbf1 Do
        While ((tdDbf1.FieldByName('Key').As...=myKey) and Not
(tdDbf1.Eof)) Do
        begin
         // If Index KEY is "Ascending"
          tdDbf1.Next;
         (// OR: If Index KEY is "Descending"
          tdDbf1.Previous ; ) // depending on what are your needs...
        end;
      You also have tbClientes.MoveBy(...); i don't know if it suit's
your needs.  I gess not!?

I hope it help's
B.Regards
Mário

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ahiggins · 2016-08-24 16:34

What DB are you using?

if you are using TDbf then you could use a filter or SetRange (index
required) then just use Next/Prev


kind regards

Tony