[V4RB] updating records ... where am i going wrong?

[Ruslan Zasukhin]

on 5/12/03 8:39 PM, Pedro fp at lists at pedro.net.au wrote:

> My moon table database has a field duration which is the difference in
> new moon time between the current & next moon phase. An important note
> is that the date & time data is as Julian Date Time numbers which are
> doubles that encapsulate both date & time for a given moment which
> means that time differences can be calculated by simple decimal
> subtraction. In my source data file the durations values are faulty so
> I added this method called after import ...
> 
>  dim i As integer, c As vCursor, b As boolean, nNew, nCur As double
>  dim newPhase, newDuration As vDouble
> 
>  c = mDatabase.SQLselect( "SELECT phase1, duration FROM moon ORDER BY
> phase1" ) ' WHERE RecID > 0
> 
>  if c.recordCount > 0 then
>    ' Assign cursor fields to variables.
>    newPhase = c.doubleField( "phase1" )
>    newDuration = c.doubleField( "duration" )
> 
>    for i = 1 to ( c.recordCount - 1 )
>      c.currentPosition = i + 1 ' Go to the record ahead.
>      nNew = newPhase.value ' Get the next new moon.
>      c.currentPosition = i ' Go back to the current record.
>      nCur = newPhase.value ' Get the current new moon.
>      writeLog "nNew = " + str( nNew ) + ", nCur = " + str( nCur ) + ",
> duration = " + str( nNew - nCur )
>      newDuration.value = nNew - nCur ' Set duration as the difference.
>    next
> 
>    b = c.updateAll

>    mDatabase.baseObject( "moon" ).flush
>  else
>    msgBox "Failed to get cursor for updating."
>  end if
> 
> The writeLog line shows me that the differences are being calculated
> but when the data loads to my listbox all the differences are zero. Any
> clues as to what I'm doing wrong?

You not correctly understand how works UpdateAll().

Think about UpdateAll() as standard SQL command:

    UPDATE T set f1 = x WHERE RecID > 0

So ALL records get the same value.
UpdateAll must not be called after loop, but after SIGNLE set of fields
values. 

Pedro, I think for you task you should simply use Update()


   dim i As integer, c As vCursor, b As boolean, nNew, nCur As double
   dim newPhase, newDuration As vDouble

   c = mDatabase.SQLselect( "SELECT phase1, duration FROM moon ORDER BY
phase1" ) ' WHERE RecID > 0

   if c.recordCount > 0 then

     ' Assign cursor fields to variables.
     newPhase = c.doubleField( "phase1" )
     newDuration = c.doubleField( "duration" )
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ VERY GOOD :-)

     for i = 1 to ( c.recordCount - 1 )
       c.currentPosition = i + 1 ' Go to the record ahead.
           nNew = newPhase.value ' Get the next new moon.
       c.currentPosition = i ' Go back to the current record.

       nCur = newPhase.value ' Get the current new moon.
       newDuration.value = nNew - nCur ' Set duration as the difference.
       c.Update() 
     next


     mDatabase.baseObject( "moon" ).flush
   else
     msgBox "Failed to get cursor for updating."
   end if



-- 
Best regards,
Ruslan Zasukhin      [ I feel the need...the need for speed ]
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e-mail: ruslan at paradigmasoft.com
web: http://www.paradigmasoft.com

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