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Checking is_required property of ms access table fields

Posted on 2008-10-26
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Last Modified: 2013-11-29
Hi,
Im using the following code for checking the 'nullable' property of ms access table fields with name 'tablename' and field 'fieldname' passed as variables to the function and returning 'NOT NULL' string. The function should check if the field is a 'is_required' field type.
Unfortunately, Im not getting the desired result ie. Primary key fields dont return a 'NOT NULL'. Any idea why this might be? Any help will be much appreciated

function GetRequired(ADOConnection: TADOConnection; tablename:string; fieldname:string):string;
var
fieldreq: TADODataSet;
i: integer;
comparefield: integer;
output: boolean;
begin
  fieldreq := TADODataSet.Create(nil);
  fieldreq.Connection := ADOConnection;
try
ADOConnection.OpenSchema(siColumns,VarArrayOf([Unassigned,Unassigned,tablename,Unassigned]),EmptyParam,fieldreq);
 
for i := 0 to fieldreq.RecordCount-1 do
  begin
comparefield :=AnsiCompareStr(fieldreq.FieldByName('COLUMN_NAME').AsString, fieldname);
if comparefield = 0 then begin
output := fieldreq.FieldByName('IS_NULLABLE').AsBoolean;
  if output
    then fieldreq.Next
  else result := 'NOT NULL';
end
else
fieldreq.Next;
end;
finally
fieldreq.Free;
end;
end;

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Question by:sbahri
1 Comment
 
LVL 74

Accepted Solution

by:
Jeffrey Coachman earned 375 total points
ID: 22810450
sbahri,

Primary keys, by design, cannot be null.
So even if you set the Required property to No, you will not be able to leave it blank.
So you may want to somehow exclude/ignore them in your code.

JeffCoachman
0

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