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Make blank cell in Delphi "You cannot add or change a record because a related record is required..."

Posted on 2011-09-10
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Last Modified: 2012-05-12
I'm using Delphi with an MS Access Database.

I have two tables

Kid Names
==========
John
Mary
Paul

Class List
===========
Grade | Name
-------  ---------
Grade 2 | John
Grade 7 |
Grade 3 | Mary

Now for some reason, in Delphi, once a cell is modified, it will not let me change it to a BLANK cell again.

Yes these two tables are in a relationship.

But Delphi is OK with the cell being a blank cell--BEFORE a change is propagated. But once you propagate a change, and try to go blank again, you get the error message in the Title of this thread.

This is obviously because, there is no blank cells in table KIDS NAMES.

So how do i find a way to specify that I do not wish to assign a kid to GRADE 7 at this time. e.g. i want to leave it blank for now...?
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Question by:bobbysdog
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3 Comments
 
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Accepted Solution

by:
epasquier earned 500 total points
ID: 36517459
you don't want blank (empty string) but NULL value
something like this

procedure SetClassKid(KidName:String);
Var
 fldName:TField;
begin
 fldName:=tblClassList.FieldByName('NAME');
 if KidName<>''
  Then fldName.Value:=KidName
  Else fldName.Clear;  // set this field to NULL
end;
0
 

Author Comment

by:bobbysdog
ID: 36517591
Yaaaay

Right - the solution was to make it NULL

I used this line to do it:

ADOTable1.FieldValues['KidsName'] := Null;

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Author Closing Comment

by:bobbysdog
ID: 36517593
Thanks!
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