[DUG] Runtime user defined fields

[Rohit Gupta]

Russell,

you made it much clearer than I did :-)

I actually use TFieldType from Delphi and only support 4 types.  I dont 
have any issue with searching

where (Field_Type = ftInteger) and (Field_Data between 5 and 6)

where (Field_Type = ftstring) and (Field_Data = 'GLUCOSE')

work just fine.



Rohit

On 6/03/2013 12:45 p.m., russell 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
> *Fax *4892290
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-- 
Regards

*Rohit Gupta*
B.E. Elec., M.E., Mem IEEE, Member IET
Technical Director
Computer Fanatics Ltd

*Tel *4892280
*Fax *4892290
*Web *www.cfl.co.nz
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