Subject Re: using a query as variable : question does anyone some opinions
From Dirk C <dirk@C.com>
Date Fri, 31 May 2024 23:02:20 +0200
Newsgroups dbase.getting-started

  Mervyn,

  thanks for more insight into
  your suggestion form.processRow() : such a function gave me already
  more inspiration semi automate this programm, just think about it

  the difference between procedure and function ( altough by dBase the
same) is a bit confused

have a nice weekend

Dirk,


Op 31/05/2024 om 17:14 schreef Mervyn Bick:
> On 2024/05/30 21:00, Dirk C wrote:
>> Hello
>> the following is working, but like to have som opinion about
>>
>> using thh query build on form or create a variable of a query
>>
>> both are working, but i am wondering if to catch the variable is more
>> stable
>
> One of the Golden Rules of programing is "If it works, it's not wrong.".
> :-) There may, however, be a simpler, better, faster, more elegant (take
> your pick :-) ) way of doing it.
>
> The main reason for saving a query (or any object for that matter) to a
> memory variable is to save typing later in your source code.  It makes
> absolutely no difference to dBASE whether you use
>
>       q_Cross = this.parent.vraagbak_artCon
>       q_cross.active = false
>       q_cross.sql = form.vraagbak_zoek
>       q_Cross.active = true
> or
>       form.vraagbak_artCon.active = false
>       form.vraagbak_artCon.sql = form.vraagbak_zoek
>       form.vraagbak_artCon.active = true
>
> All programmers develop a style so this is purely a personal opinion but
> I don't like changing a query's sql property in a program.  While it is
> possible with a standard query, keep in mind that this causes problems
> with an ADOquery.  Instead of using applyLocate() I prefer to use a
> parameter driven query.
>
> Back in the early days of dBASE, FUNCTIONs returned a value and
> PROCEDUREs didn't.  Over time the distinction has been removed and
> PROCEDURE as defining command has fallen into disuse.  As function
> knop_zoek_onclick() doesn't return a value it is actually a procedure.
> As a procedure it actually needs some code to deal with success or
> failure to find a matching record otherwise your program is just waiting
> for further input from the user.  Either set the cursor ready to receive
> a new search value or use the selected record to do something.
>
> In function knop_zoek_onclick() there is no need for
> q_Cross.rowset.beginlocate() which is used to allow a datalinked
> entryfield to be used to input a search value.
>
> Instead of nesting if...else...endif constructs as you have done, an
> if...elseif...else...endif construct (which works exactly like DO CASE)
> is a better option in this case as this terminates immediately a test
> returns true.
>
> If you use similar code multiple times in a function or procedure it can
> usually be factored out.  This will cut down on the size of the code and
> will usually make it easier to follow.
>
> A reworked version of function knop_zoek_onClick() follows.  It hasn't
> been tested so there may be typos.  I'm not suggesting that you change
> your existing working code but this is an approach to keep in mind for
> "next time".
>
> function knop_zoek_onclick()
>     local c_Ref1, c_Waarde1, q_Cross, c_Ref2, c_Ref3,bFound
>     c_Waarde1 = this.parent.veld_Zoek.value
>     q_Cross = this.parent.vraagbak_artCon
>     q_Cross.rowset.locateOptions = 0
>     c_Ref1 = "conartikel1 ='"+c_Waarde1+"'"
>     c_Ref2  = "conartikel2 ='"+c_Waarde1+"'"
>     c_Ref3  = "conartikel3 ='"+c_Waarde1+"'"
> //   q_cross.active = false
> //   q_cross.sql = form.vraagbak_zoek
> //   q_Cross.active = true
>     if empty(c_waarde1)
>        bFound = false
>        msgBox("data ingeven", "***** bci dataverwerking *****", 48)
>          //No search value.  Remaining tests will be skipped
>     elseif  q_Cross.rowset.Applylocate(c_Ref1) = true
>          bFound = true
>          //c_Ref1 found so rowpointer on record. Remaining tests will be
> skipped
>         //if c_Ref1 not found, try c_Ref2
>     elseif  q_Cross.rowset.Applylocate(c_Ref2) = true
>        bFound = true
>     elseif  q_Cross.rowset.Applylocate(c_Ref3) = true
>        bFound = true
>     else
>        bFound = false
>        msgbox("geen data gevonden vir "+cWaarde1)
>        form.veld_Zoek.value = ''  //Remove previous value
>        form.veld_Zoek.setFocus()   // Ready to accept a new search value
>     endif
>     if bFound = true  //A matching row was found.
>        form.processRow()  //Code to continue the program instead of
>                           //waiting for the user to press another button.
>     endif
>     return
>
>
> Mervyn.