How to join and retrieval object?

[vu-hoang]

Dear support

I have 2 tables Itinerary and Location with relation 1-1.
Itinerary Table
http://support.backendless.com/public/attachments/06f643a81f0fdc3c644fc4a4beb20308.png</img>
Location Table
http://support.backendless.com/public/attachments/1747664565e8e311800a53be18b2ae9f.png</img>

I want to query Locations which have Itineraries. Like SQL statement
“select * from location, itinerary where location.id = itenerary.location.id”

How I can do it in Backendless?

Thanks
Best Regards

[vu-hoang]

Dear support

I hope this question is not missing. I need your help

Thanks
Best Regards

[mark-piller]

Hi Vu,

The following whereClause query (sent to the Itinerary table) will get you want you want:

location.objectId = ‘specific objectId of a location object’

Regards,
Mark

[vu-hoang]

Hi Mark

Thanks your answer but it just for get result of itineraries base on location id.
In my case I want to load list locations which have itinerary reference.

Ex: I have 4 Locations A, B, C, D
I insert Itinerary 1 relate to A
I insert Itinerary 2 relate to B
=> I expect to get result A and B.

• C and D not in list because not have Itinerary

In SQL I can use Inner Join to list those locations(A,B). But in backendless I not find the way to get it yet.
Hope you understand my explain.

Thanks
Best Regards

[mark-piller]

To get locations for an itinerary, you can use the following whereClause query (query must be sent to the Location table):

Itinerary[location].objectId = 'itinerary object id'

[vu-hoang]

Hi Mark
Sr about my explain is not good.
I think you still not get my case. I just want to get locations is referenced to itinerary. Can you look again my tables?
Or can I “Select distinct location.id from Itinerary” so I can get list Location is referenced to itinerary.

Thanks

[mark-piller]

What I suggested will do exactly what you’re asking: getting all the locations referenced by a specific itinerary.

[vu-hoang]

Not by a specific itinerary. An itinerary just only have one location.
A Location is referenced by 0…n itinerary.

I want to know If locations have itineraries or not.

Thanks your patience again.

As you can see field Itinerary.location value “United State” not have any itinerary.

http://support.backendless.com/public/attachments/5a6c5b4a4c665a1066e8d17314ad04b7.png</img>

[mark-piller]

If you want to get all locations which are referenced by any itinerary, the query will look like this:

Itinerary[location].objectId is not null

To get all locations which are NOT referenced by any itinerary, then this:

Itinerary[location].objectId is null

[vu-hoang]

Hi MarkWoa thanks this is what I looking for.

It is little hard to find in your document.
Again thanks your patience. Great support

Thanks
Best Regards