Can you return data in JSON format from a web service in SQL Server?

The short answer is yes provided we run our queries in SQL Server 2016.

We have seen in an earlier post using ODATA service to generate a report from Power BI.

These were some example OData services that were considered in the previous mentioned link.

Northwind traders here:
http://services.odata.org/northwind/northwind.svc
http://services.odata.org/V4/Northwind/Northwind.svc

Adventure Works data here:
http://services.odata.org/AdventureWorksV3/AdventureWorks.svc

SQL Server 2016 supports JSON and it is possible to run a query in SQL Server Management Studio to return data from a ODATA service by running a query fashioned a shown.
=======
SELECT 'http://services.odata.org/V4/Northwind/Northwind.svc/$metadata#Products(ProductID,ProductName)/$entity' AS '@odata.context',  
ProductID, Name as ProductName  
FROM Production.Product 
WHERE ProductID<400 br="">FOR JSON AUTO 
=======
This retrieves the following result:

Note that the size of text returned is limited by the settings.