How to write cross database query in entity framework [duplicate]

Question

I am using entity framework 6.1 and I have two databases.

CustomerDB
CustomerArchiveDB

Both have a Customer table with columns Name, Address, Year etc.

I want to get all the customers from both databases using Entity Framework.

How do I do this?

Can't you query the first db then change your connection string then query the second db? — Tien Dinh
– Tien Dinh, Commented Dec 20, 2014 at 13:54

John · Accepted Answer · 2014-12-20 10:03:19Z

1

Create 2 EF models, one for each database. Materialize the objects with ToList or ToArray from each DbContext and then Concat them together in memory.

answered Dec 20, 2014 at 10:03

John

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2 Comments

PrinceT Over a year ago

both the tables have crores of data, with your approach i have to load all the data in-memory and then perform operation. which would be slow.

John Over a year ago

The problem is that one EF model can't use 2 connection strings and multiple models can't use joins. Perhaps you can tackle the problem on a lower level in the db itself by creating a view to the archived customers in your active db? Or even a joined view of both the customers tables.

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