Re: N+1 with a twist?

Nathan Maves Thu, 10 Feb 2005 15:14:49 -0800

PERFECT!

On Feb 10, 2005, at 4:07 PM, Mike Fagan wrote:

If you are using oracle the following is legal:

select p.*, c.name child_name, c.description
from parent p, child c
WHERE p.id = c.parent_id;


Nathan Maves wrote:

That is how I was going to handle them. I was just looking to see if there was some tricky way to use "select *" from multiple tables. I have one table that has 30 columns in it. It is very painful to list out each column :)

Nathan
On Feb 10, 2005, at 3:50 PM, Kris A. Jenkins wrote:

Nathan,

Ambiguous column names are easily handled.  Just
differentiate the names in the query, then you can
assign them explicitly in the resultMaps.  Here's an
example with an ambiguous 'name' column:

<sqlMap namespace="Example">
 <resultMap id="parentResult" class="com.eg.Parent"
groupBy="parentId">
  <result property="parentId" column="parent_id"/>
  <result property="name" column="parent_name"/>
  <result property="children"
resultMap="Example.childResult"/>
 </resultMap>

 <resultMap id="childResult" class="com.eg.Child">
  <result property="name" column="child_name"/>
  <result property="description"
column="description"/>
column="broadcastEndDate"/>
 </resultMap>

 <select id="getFamilies" resultMap="parentResult">
  select
    p.id AS parent_id,
    p.name AS parent_name,
    c.name AS child_name,
    c.desc AS description
  FROM child c, parent p
  WHERE p.id = c.parent_id
</select>
</sqlMap>

In this example both the column and the property names
are ambiguous, but it's gracefully handled. :-)

HTH,
Kris

 --- Nathan Maves <[EMAIL PROTECTED]> wrote:

Great!  I will give it a try.
What do you suggest when you have ambiguously
defined column names in a
n+1 query?
nathan
On Feb 9, 2005, at 10:30 AM, Clinton Begin wrote:
If you can join the data into a single resultset
with repeating
groups, the N+1 solution will work, no matter how
the collections are
arranged.
As long as you group by some column in table_a,
you can separately map
2 collections on the same class.
This will work.
Try it out!
Clinton
On Wed, 09 Feb 2005 10:21:54 -0700, Nathan Maves
<[EMAIL PROTECTED]> wrote:
I dont think that the current implementation will
work for this but I
was looking for some best practices on how to do
it.
Parent Class A has n number of List properties
that all come for their
own tables.
A from table_a
        List of B from table_b
        List of C from table_c
        .
        .
        .
Nathan

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Re: N+1 with a twist?

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