Newbie question - How can I run the following Query in ActiveRecord?

Rails
#1

I’m totally rails newbie, and just started it a couple of days ago
moving from PHP, so I’ve the following query, and want to know how can
I do it using ActiveRecord

SELECT sites., snapshots., technologies.*
FROM sites, snapshots, technologies
WHERE sites.id = ‘1’
AND snapshots.site_id = sites.id
AND technologies.snapshot_id = snapshots.id

#2

On 11 November 2011 12:02, Mahmoud Abdel-Fattah
[email protected] wrote:

I’m totally rails newbie, and just started it a couple of days ago
moving from PHP, so I’ve the following query, and want to know how can
I do it using ActiveRecord

SELECT sites., snapshots., technologies.*
FROM sites, snapshots, technologies
WHERE sites.id = ‘1’
AND snapshots.site_id = sites.id
AND technologies.snapshot_id = snapshots.id

Don’t think about queries, think about relationships. If you setup
the has_many and belongs_to relationships then if you have a Site in
@site then its snapshots are @sites.snapshots and for a given snapshot
then its technologies are snapshot.technologies. Let Rails worry
about the queries.

Any newcomer is well advised to work through some tutorials to
understand what rails can do. railstutorial.org is good and is free
to use online. Also work through the Rails Guides.
Make sure any tutorial you use is for the right version of Rails.

Colin

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#3

I think what you are trying to do is joins

if your associations are set correctly, then something like below should
work

Site.joins(:snapshots).joins(:technologies).where(“sites.id=1”)

*Note: *in the where clause, you cannot use :id=>1 because :id with
the
joined tables will be ambigious… you have to state explicitly the
table
of which the id to be used

On Fri, Nov 11, 2011 at 2:02 PM, Mahmoud Abdel-Fattah <
[email protected]> wrote:

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Mahmoud Said
Software Engineer - eSpace
blog.modsaid.com