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Editorial Team
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Asked: 2026-05-31T12:45:08+00:00

I’m using C#, .NET (4.0) and Entity Framework to connect to SQL CE 4.0.

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I’m using C#, .NET (4.0) and Entity Framework to connect to SQL CE 4.0.

I query some objects with specific properties, but the query returns only objects that meet search criteria only if that data was already saved to database, which is not that problematic, bigger problem is that if data is changed, but not yet saved to database it will still meet search criteria.

Example:

var query = from location in mainDBContext.Locations
            where location.InUse == true
            select location;

This query returns also objects where location.InUse = false if InUse was true when loaded from DB and then changed later on in code.

This is screen capture from one of the query results objects.

enter image description here

I really don’t understand why it does this. I would understand if this query would always query database and I would get the older version of this object (thus InUse would be true).

Thank you for your time and answers.

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1 Answer

  1. Editorial Team

    That is how EF works internally.

    Every entity uniquely identified by its key can be tracked by the context only once – that is called identity map. So it doesn’t matter how many times did you execute the query. If the query is returning tracked entities and if it is repeatedly executed on the same context instance it will always return the same instance.

    If the instance was modified in the application but not saved to the database your query will be executed on the database where persisted state will be evaluated but materialization process will by default use the current data from the application instead of data retrieved from the database. You can force the query to return state from the database (by setting mainDBContext.Locations.MergeOption = MergeOption.OverwriteChagens) but because of identity map your current modifications will be lost.

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