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Delphi 7 : Lookup Field?

Posted on 2007-11-19
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Last Modified: 2013-11-23
Hi Experts,

I have an TDBGrid and would like the use to be able to pick from a dropdown in the list.
For example:

Table1:
ColorID INT PK
ColorCode VARCHAR(10)
Description VARCHAR(100)

Table2:
VehicleID INT PK
ColorID INT
RegNumber VARCHAR(20)


When inserting a new row in the DBGrid for Table2, I would like to user to be able to select from dropdown in grid from all the available colorcodes and after selecting the ColorID should be saved in this table.

I managed to get what I am looking by means of creating a new lookup field on my ADOTable Component for Table2. But when inserting a new row I receive the following error:

"raised exception class EOleException with message 'An unkown error has occurred.' Process stopped...."

Please advise.
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Question by:Marius0188
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17 Comments
 
LVL 21

Assisted Solution

by:developmentguru
developmentguru earned 150 total points
ID: 20312096
We would need to see your code for starters.  There is nothing wrong with how you are handling the lookup field, that in itself should not cause an error.  I suspect that something was missing in how it was set up.  Can you show us a simplified example?
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Author Comment

by:Marius0188
ID: 20312820
Here is a screenshot of my setup:
http://www.medalware.com/delphi_lookup.JPG

I use a normal TDBGrid and TADOTable components.

Thanks!
0
 
LVL 18

Assisted Solution

by:Johnjces
Johnjces earned 150 total points
ID: 20315434
I am confuised, but that is pretty normal for me...

Are you storing in your dataset the color as a string name such as clRed, or clBlack or are you storing the actual color identifier, which will be a hex value such as $000000FF, (decimal 255 which is clRed) .

ColorID as an Int sounds OK if you are storing the color value, but I do not know about what you are storing in ColorCode and if that is like clRed.

Not sure if it is a table/database issue or some other code part failing when getting the color.

A code snippet or two will really be helpful as developmentguru has suggested. A picture can be worth a thousand words, but...

John
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Author Comment

by:Marius0188
ID: 20319069
I have build a demo app using Firebird database and Interbase components.
I have created a lookup table exactly as I have done with the ADO table components and it is WORKING here.

I guess there is something else about the TADOTable component.
Let me see if I can provide you with a demo.


Cheers
0
 

Author Comment

by:Marius0188
ID: 20319183
Ok I have produced a demo for you:
http://www.medalware.com/demo_lookup.zip

Just connect both TIBDatabase & TADOConnection components to the databasis that is in a subfolder.
1 x Firebird DB
1 x MS SQL MDF DB

The firebird is working 100%.
The SQL db is giving me that nasty exception.


Thanks in advance!

0
 

Author Comment

by:Marius0188
ID: 20319221
It looks like a bug in ADO.
http://qc.codegear.com/wc/qcmain.aspx?d=46248

Is there any work arounds?
Where can I get the latest Delphi 7 updates?


Thanks!
0
 

Author Comment

by:Marius0188
ID: 20319310
Can one connect to SQL 2005 db without using ADO components?
Is there any other good alternative components or methods one can try?
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LVL 8

Accepted Solution

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RickJ earned 200 total points
ID: 20331714
Hello marius0188,
I downloaded and tried your example and it works fine for me.
Guessing it may be something that was fixed with the delphi 7 service update 1. Do you have that installed?
I think you need to be a registered user to download it.

Rick.
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Author Comment

by:Marius0188
ID: 20332773
Yes I do have that update.
But if I remember correctly, when installing that update it prompt to notify me about missing files where after I just clicked ignore. Maybe it has something to do with that.

Mmmmh, I wonder if I can just update the ADO dcu's etc by getting them from you.
Will that not work?
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LVL 8

Expert Comment

by:RickJ
ID: 20333275
Much cleaner to get your intall to work correctly, but worth a shot I guess.
Would back up before attempting.
Here you go.
http://www.logancontracting.com.au/ado/ado.zip
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Author Comment

by:Marius0188
ID: 20333516
Nope, still not working.

Are you also using Delphi 7 Enterprise?
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LVL 8

Expert Comment

by:RickJ
ID: 20333530
Delphi 7 pro. I would have thought the ado stuff would have been the same. But I could be wrong.
Not sure how else I can help you...
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Author Comment

by:Marius0188
ID: 20333790
You don't think it might be the TDBGrid component?
Maybe you must sent me your source and let me try that.

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LVL 8

Expert Comment

by:RickJ
ID: 20336974
I still think getting your install correct would be a better way to go. But again,
Here you go.
http://www.logancontracting.com.au/ado/dbgrids.zip
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Author Comment

by:Marius0188
ID: 20337406
Yip, after this one I will go for re-install and then apply that 7.1 update.
But need a quick fix because installing all my components from start takes 1-2 days.

Enjoy
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Author Comment

by:Marius0188
ID: 20337417
Ok but another thing is:
It is only in the compiler (IDE) that I get the exception EOleException.

When running outside the IDE no problem.
Should I still be worried?
0
 

Author Comment

by:Marius0188
ID: 20372089
Ok I will accept that this might be an installation problem.
Have not tested yet but will try to re-install as soon as I have time available.

Lets split the points....

Thanks to all!
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