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: [email protected] [mailto:[email protected]] 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 _______________________________________________ NZ Borland Developers Group - Delphi mailing list Post: [email protected] Admin: http://delphi.org.nz/mailman/listinfo/delphi Unsubscribe: send an email to [email protected] with Subject: unsubscribe __________ Information from ESET Endpoint Antivirus, version of virus signature database 8081 (20130305) __________ The message was checked by ESET Endpoint Antivirus. http://www.eset.com -- 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 _____ This email and any attachments contain information, which is confidential and may be subject to legal privilege and copyright. If you are not the intended recipient, you must not use, distribute or copy this email or attachments. If you have received this in error, please notify us immediately by return email and then delete this email and any attachments.
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