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<div class="moz-cite-prefix">Russell, <br>
<br>
you made it much clearer than I did :-)<br>
<br>
I actually use TFieldType from Delphi and only support 4 types. I
dont have any issue with searching<br>
<br>
where (Field_Type = ftInteger) and (Field_Data between 5 and 6) <br>
<br>
where (Field_Type = ftstring) and (Field_Data = 'GLUCOSE')<br>
<br>
work just fine.<br>
<br>
<br>
<br>
Rohit<br>
<br>
On 6/03/2013 12:45 p.m., russell wrote:<br>
</div>
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<div class="WordSection1">
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Rohit’s
method is like one I use that allows users to “add fields”.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Users
add records to an existing table. The program manages these
records (so it appears to users) as if they are fields.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
field types are important if you allow users to store data
that will not fit into a fixed length field. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">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.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">All
three types are stored as BLOBs in a Firebird db file.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">A
“con” is these fields are not easily searched … but I do not
need this ability.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Best
regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Russell<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"
lang="EN-US">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"
lang="EN-US"> <a class="moz-txt-link-abbreviated" href="mailto:delphi-bounces@listserver.123.net.nz">delphi-bounces@listserver.123.net.nz</a>
[<a class="moz-txt-link-freetext" href="mailto:delphi-bounces@listserver.123.net.nz">mailto:delphi-bounces@listserver.123.net.nz</a>] <b>On
Behalf Of </b>Rohit Gupta<br>
<b>Sent:</b> Wednesday, 6 March 2013 11:49 a.m.<br>
<b>To:</b> NZ Borland Developers Group - Delphi List<br>
<b>Cc:</b> List NZ Borland Developers Group - Delphi<br>
<b>Subject:</b> Re: [DUG] Runtime user defined fields<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">I would consider having a generic table
where you soft-add the fields<br>
<br>
Ref_Num : autoinc<br>
Owner_Num : int64<br>
Field_Name : string (16)<br>
Field_Type : integer // ord(TFieldType)<br>
Field_Data : string (255) // store everything as string
but the type above tells you what it is<br>
<br>
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.<br>
<br>
Regards<br>
<br>
Rohit<br>
<br>
On 6/03/2013 10:41 a.m., Steve Peacocke wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<pre>Hi everyone,<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>I've been away from programming for a while so please excuse the<o:p></o:p></pre>
<pre>seemingly simple question.<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>I'm designing a user interface for a new application and wondered if<o:p></o:p></pre>
<pre>there was a generally accepted way that this "should" be done.<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>The application will allow end users to edit their forms allowing them<o:p></o:p></pre>
<pre>to add, move, and remove fields at runtime. I'm using MySQL but I was<o:p></o:p></pre>
<pre>wondering if there was an accepted way of adding and changing fields<o:p></o:p></pre>
<pre>to a database.<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>I know I can use SQL for this but I also don't want to make every<o:p></o:p></pre>
<pre>application unable to be managed or upgraded. Perhaps I can ensure<o:p></o:p></pre>
<pre>that the 3-4 permanent fields are never able to be altered (ID, Name,<o:p></o:p></pre>
<pre>etc) but allow the user (through a suitable user-friendly interface)<o:p></o:p></pre>
<pre>to go crazy adding such fields as My_favourite_colour, Rating,<o:p></o:p></pre>
<pre>Priority, Notes, etc. etc.<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>I'm able to give a suitable user-friendly interface to allow them to<o:p></o:p></pre>
<pre>physically alter the Delphi form at runtime, but wondered about the<o:p></o:p></pre>
<pre>"most appropriate way" to modify the fields to the database.<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>1. I could simply add fields using SQL's ALTER TABLE<o:p></o:p></pre>
<pre>2. I could add another table with fields such as TableName, FieldName,<o:p></o:p></pre>
<pre>Type, etc.. and add to that<o:p></o:p></pre>
<pre>3. Some other spiffy way that you people will suggest that I haven't<o:p></o:p></pre>
<pre>even thought of yet.<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>Any suggestions?<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre><o:p> </o:p></pre>
<pre>Steve Peacocke<o:p></o:p></pre>
<pre>+64 220 612-611<o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="http://www.nzorient.co.nz">http://www.nzorient.co.nz</a><o:p></o:p></pre>
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<p class="MsoNormal">-- <br>
Regards<br>
<br>
<b>Rohit Gupta</b><br>
B.E. Elec., M.E., Mem IEEE, Member IET<br>
Technical Director<br>
Computer Fanatics Ltd<br>
<br>
<b>Tel </b>4892280 <br>
<b>Fax </b>4892290 <br>
<b>Web </b><a moz-do-not-send="true" href="www.cfl.co.nz">www.cfl.co.nz</a><o:p></o:p></p>
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Regards<br>
<br>
<b>Rohit Gupta</b><br>
B.E. Elec., M.E., Mem IEEE, Member IET<br>
Technical Director<br>
Computer Fanatics Ltd<br>
<br>
<b>Tel </b>4892280 <br>
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