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From "Collin Peters" <cadio...@gmail.com>
Subject Re: 1:N:M
Date Thu, 05 Jul 2007 22:21:19 GMT
I think this is the same request:
https://issues.apache.org/jira/browse/IBATIS-396

On 7/5/07, Collin Peters <cadiolis@gmail.com> wrote:
> I can't seem to get this to work.  I will try to explain a full example here.
>
> Imagine the following data structure:
> -ObjectA has a List of ObjectB's (1:M)
> -ObjectB has a variable ObjectC (1:1)
> -Object C has three children lists (Child1, Child2, Child3 - all 1:M)
>
> The SQL looks something like (postgresql syntax)
> SELECT a.object_a_id, b.object_b_id, c.object_c_id
> FROM object_a a
> JOIN object_b b USING (object_a_id)
> JOIN object_c c USING (object_b_id)
> JOIN child_1 c1 USING (object_c_id)
> JOIN child_2 c2 USING (object_c_id)
> JOIN child_3 c3 USING (object_c_id)
>
> This SQL would obviously return multiple rows with duplicate data.
> Assuming there was 2 rows for each of the three children you would get
> 8 rows for each ObjectC
>
> child_1_id  | child_2_id  |  child_3_id
> 1               | 1              | 1
> 2               | 1              | 1
> 1               | 2              | 1
> 2               | 2              | 1
> 1               | 1              | 2
> 2               | 1              | 2
> 1               | 2              | 2
> 2               | 2              | 2
>
> Now in iBatis I would like to get a result of one ObjectC that has a
> List of 2 objects for each of the children.  The result I am getting
> is 2 objects for the Child1 List, 4 objects for the Child2 List, and 8
> objects for the Child3 List.
>
> Is this example clear enough?  I suppose I can do a code example if required.
>
> Another strange thing I have found is that iBatis does not complain if
> the groupBy uses a meaningless string.  Meaning I can have
> groupBy="foo" and I do not get any errors ('foo' is not a column in
> the table or POJO.  Is this behavior to be expected?
>
> Regards,
> Collin
>

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