[DUG] Runtime user defined fields

Wed Mar 6 17:50:29 NZDT 2013

I would extend to Rohits idea a little to allow granularity and the ability
to create dynamic search queries by creating a table structure for each
field type so that I can store and index the field data natively.

Any queries can be slow on this type of dynamic structure, but if each form
data is bound by a common header id then you can even create a view for a
form data, by using a Table Select for each field..

Select

 (select Value from IntTable where ID = @HeaderID and FieldID = @FieldID)
Age,
(select value from strTable where Id = @HeaderiD and FieldID = @FieldID)
Surname

from FormHeaderData where HeaderID = @HeaderID

The above queries can all be dynamically generated by you on each site and
rebuilt as Stored Procedures for speed.

On Wed, Mar 6, 2013 at 12:45 PM, russell <russell at belding.co.nz> wrote:

> Rohit’s method is like one I use that allows users to “add fields”.****
>
> ** **
>
> Users add records to an existing table. The program manages these records
> (so it appears to users) as if they are fields.****
>
> The field types are important if you allow users to store data that will
> not fit into a fixed length field. ****
>
> ** **
>
> I allow three data types: Text, FileNames and Memo. The first two are
> single lines of text of any length and the third handles multi-line data.*
> ***
>
> All three types are stored as BLOBs in a Firebird db file.****
>
> ** **
>
> A “con” is these fields are not easily searched … but I do not need this
> ability.****
>
> ** **
>
> Best regards,****
>
> Russell****
>
> ** **
>
> *From:* delphi-bounces at listserver.123.net.nz [mailto:
> delphi-bounces at listserver.123.net.nz] *On Behalf Of *Rohit Gupta
> *Sent:* Wednesday, 6 March 2013 11:49 a.m.
> *To:* NZ Borland Developers Group - Delphi List
> *Cc:* List NZ Borland Developers Group - Delphi
> *Subject:* Re: [DUG] Runtime user defined fields****
>
> ** **
>
> I would consider having a generic table where you soft-add the fields
>
> Ref_Num : autoinc
> Owner_Num : int64
> Field_Name : string (16)
> Field_Type : integer // ord(TFieldType)
> Field_Data  : string (255)  // store everything as string but the type
> above tells you what it is
>
> This way you dont alter the database.  You dont have to worry about
> indexes etc.  Everyones database is the same.  Yet you can search for data
> for a particular field name.  I am actually using this structure in a three
> projects.
>
> Regards
>
> Rohit
>
> On 6/03/2013 10:41 a.m., Steve Peacocke wrote:****
>
> Hi everyone,****
>
> ** **
>
> I've been away from programming for a while so please excuse the****
>
> seemingly simple question.****
>
> ** **
>
> I'm designing a user interface for a new application and wondered if****
>
> there was a generally accepted way that this "should" be done.****
>
> ** **
>
> The application will allow end users to edit their forms allowing them****
>
> to add, move, and remove fields at runtime. I'm using MySQL but I was****
>
> wondering if there was an accepted way of adding and changing fields****
>
> to a database.****
>
> ** **
>
> I know I can use SQL for this but I also don't want to make every****
>
> application unable to be managed or upgraded. Perhaps I can ensure****
>
> that the 3-4 permanent fields are never able to be altered (ID, Name,****
>
> etc) but allow the user (through a suitable user-friendly interface)****
>
> to go crazy adding such fields as My_favourite_colour, Rating,****
>
> Priority, Notes, etc. etc.****
>
> ** **
>
> I'm able to give a suitable user-friendly interface to allow them to****
>
> physically alter the Delphi form at runtime, but wondered about the****
>
> "most appropriate way" to modify the fields to the database.****
>
> ** **
>
> 1. I could simply add fields using SQL's ALTER TABLE****
>
> 2. I could add another table with fields such as TableName, FieldName,****
>
> Type, etc.. and add to that****
>
> 3. Some other spiffy way that you people will suggest that I haven't****
>
> even thought of yet.****
>
> ** **
>
> Any suggestions?****
>
> ** **
>
> ** **
>
> Steve Peacocke****
>
> +64 220 612-611****
>
> http://www.nzorient.co.nz****
>
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>
> --
> Regards
>
> *Rohit Gupta*
> B.E. Elec., M.E., Mem IEEE, Member IET
> Technical Director
> Computer Fanatics Ltd
>
> *Tel *4892280
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-- 
Kyley Harris
Harris Software
+64-21-671-821
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