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Re: Store empty string to database [message #37584 is a reply to message #37581]

Sat, 20 October 2012 18:17

mirek
Messages: 13975
Registered: November 2005

Ultimate Member

dolik.rce wrote on Sat, 20 October 2012 10:29

Hi everyone!

Is it possible to differentiate between empty string and NULL in a database? As far as I can tell, storing "", e.g. in Insert(), always results to NULL being inserted. I believe it is because in U++ empty string is considered to be Null.

Correct. This is long running issue. Originaly, U++ inherited this from Oracle. In around 2001, we have shortly experimented with !IsNull(String()), but we have found this causing even more problem (e.g. for integer values, it is logical that "empty" EditInt yields Null. So it is sort of expected that empty EditString is Null). So we have reverted and restored IsNull(String()) behaviour.

Quote:

Is there some workaround to this? I can easily imagine cases where one needs to differentiate between NULL and "" in databases.

At this moment, no. In the past, we tried String::GetZero() as special value representing empty string in DB... Never got actually used and supported in Sql, so was removed. If we are about to restore something like this, I think it should go along this line (e.g. SqlEmptyString() and IsSqlEmptyString()).

Mirek

Mirek

[Updated on: Sat, 20 October 2012 18:18]

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