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From Marieke Vandamme <marieke.vanda...@tvh.be>
Subject Re: setNull in select doesn't work
Date Mon, 24 Jul 2006 12:22:33 GMT


When using other Database Drivers (like postgres) this is supported.
When suggesting Derby doesn't, what are the alternatives for my problem?
I really need to use it in the form of PreparedStatement,
like "select * from table where value = ?",
because we are using select statement with more than 6 parameter-values.

In what ways is the setNull function usefull ? 
When trying to solve my problem, in many examples I found :
if (value == null)
        ps.setNull(1, Types.VARCHAR);
        ps.setString(1, value);

Thanks !


Marieke Vandamme <marieke.vandamme@tvh.be> writes:

> Hello,
> We are trying to perform a select query to the Derby database with 
> PreparedStatement
> PreparedStatement ps = c.prepareStatement("select * from table where 
> = ?");
> //several methods performed on statement (separately ofcourse)
> 1. ps.setNull(1,Types.VARCHAR);
> 2. ps.setObject(1, null, Types.VARCHAR);
> 3. ps.setString(1, null) ;
> The table contains null values, but the resultset is empty for the 3 
> cases.

It doesn't return any rows because "value = null" does not evaluate to
true even when value in fact is null, in which case it evaluates to
unknown. "value is null" should work.

Knut Anders

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