Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.programmer > #32137 > unrolled thread

hibernate question (weird problem)

Back to article view | Back to comp.lang.java.programmer

Contents

  hibernate question (weird problem) Peter <mcheung63@hotmail.com> - 2015-07-25 17:10 +0800
    Re: hibernate question (weird problem) Arne Vajhøj <arne@vajhoej.dk> - 2015-07-25 15:22 -0400
      Re: hibernate question (weird problem) mcheung63@gmail.com - 2015-07-25 23:25 -0700

#32137 — hibernate question (weird problem)

Hi
    I am using hibernate, i got two class "JMPDATA" and "PARAMETER", 
they are linked together. Then I execute :

session.createSQLQuery("SELECT a.* from JMPDATA").addEntity(JmpData.class);

I didn't join table parameter, but i still able to get the value of it, why?

iterator = query.list().iterator();
while (iterator.hasNext()) {
	JmpData d = iterator.next();
	for (Parameter p : d.parameters) {
		System.out.println("\t" + p.name);
	}
}

I am using H2 database, and i enable the trace log, i saw the h2 is 
receive this sql command from hibernate. I am sure it didn't left join 
the parameter table.

SELECT a.* from JMPDATA as a limit ?

thanks
from Peter (cmk128@hotmail.com)

[toc] | [next] | [standalone]

#32141

On 7/25/2015 5:10 AM, Peter wrote:
>     I am using hibernate, i got two class "JMPDATA" and "PARAMETER",
> they are linked together. Then I execute :
>
> session.createSQLQuery("SELECT a.* from JMPDATA").addEntity(JmpData.class);
>
> I didn't join table parameter, but i still able to get the value of it,
> why?
>
> iterator = query.list().iterator();
> while (iterator.hasNext()) {
>      JmpData d = iterator.next();
>      for (Parameter p : d.parameters) {
>          System.out.println("\t" + p.name);
>      }
> }

You are using an OO model not plain SQL.

There is a relationship between the classes and
Hibernate correctly handles that.

Arne

[toc] | [prev] | [next] | [standalone]

#32147

i think i got the answer, if i just run that query only, hilbernate will invoke sql to get the data from subtable. if i queried those row before, then it wont. i think hibernate cached it already.
thanks
from Peter

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.java.programmer

csiph-web