Cross site lookup

[Jeyganesh]

We are using SharePoint online we would like to access top-level site list data to subs site.

for example, we created the customer list in the top-level site. we need to use this data to all subsite list.

how we can do this?

[#2]

Unfortunatelyh this is not possible with SPO Today, so to meet this requirement you need custom development

[#3]

@Jeyganeshthird-party solutions exist for these kind of scenario's. I know they exist but haven't used them myself.

However, you could consider to make use of Managed Metadata Term Sets instead of SharePoint lists. You could for example create a Customers Term Set to store the most important data to be able to identify a customer and reference this using Managed Metadata columns from all your subites. If you need to store more data around these same customers you might still also have your central "Customers" list optionally also pointing to this same Term Set and create a custom developed synchronization mechanism to prevent maintenance of your customer lists in more than one place.

Hope this helps!

[#4]

Depending on the list providing data you might be able to get by with utilizing Managed metadata, which you can setup lists of data which can be used as columns in all your sites and managed in one location.

[#5]

Our existing SharePoint site is SharePoint server 2013. there we used Site columns in the top-level site and used the lookup field to all subsite. this feature is not supported SharePoint Online?

[#6]

This scenario, in the way it worked in your SharePoint 2013 environment with subsites, still works exactly the same in SharePoint Online and is also supported. Perhaps you should consider moving to more modern site structure using multiple site collections and hub sites but that's another topic.

"Cross site" typically refers to the use of multiple site collections. Having lookups across site collections is not supported out of the box.