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Hi,

I've got a serious problem with SDAC and TMemoFields. In SQL Server database I have a field 'some_text' (text, not null) and if I try to set the FieldValue to '' (empty) then it is sent as null and I get an exception.

Steps to reproduce:
The table conatins a record (id,...,some_text,...)=(1,...,'',....) Here we have (in debug):
MsQuery.FieldValues['some_text'] = '' [OK]
MsQuery.FieldByName('some_text').IsNull = false [OK]
Now we have (in debug):
MsQuery.FieldValues['some_text'] = '' [OK]
MsQuery.FieldByName('some_text').IsNull = true [WRONG]
Exception:
Cannot insert the value NULL into column 'some_text', table 'mydb.dbo.my_table; column does not allow nulls. UPDATE fails.

The same problem exists also with calling Append/Post but only with TMemoFields, with TStringFields everything is OK.

I see this as some kind of a global DAC issue with TMemoFields, because the same situation occurs in MyDac (IsNull=true) but at least the Post doesn't raise an exception there.

Regards,
Crafty

The reason of such behaviour is code in DB.pas unit. Please take a look at the TBlobField.GetIsNull method.

Antaeus wrote:The reason of such behaviour is code in DB.pas unit. Please take a look at the TBlobField.GetIsNull method.

OK, but in that case what is your solution to the problem?
Can you somehow overcome this and allow me to save my empty memo?

Try to handle this situation by triggers, or use a stored procedure to insert values into the table.

You call this a solution?
If Delphi doesn't distinguish empty and null then you should implement some changes and post '' (empty) when it's required by database and not backstab SDAC users.

P.S. I tried to edit DB.pas and it now returns false for IsNull but SDAC still tried to post null to database