How to Perform Case-Sensitive Comparisons in LINQ to Entities?

LINQ to Entities: Achieving Case-Sensitive Comparisons

LINQ to Entities queries often inherit the case-insensitive nature of SQL Server. This guide explores methods to enforce case-sensitive comparisons within LINQ to Entities queries.

Understanding Case-Insensitive Behavior

LINQ to Entities translates queries into SQL. SQL Server's default collation is case-insensitive, meaning "Name == 'ThingamaBob'" is treated as a case-insensitive match.

Database-Level (Server-Side) Solution

The most efficient approach is to modify the database column's collation to be case-sensitive. Use a SQL statement like this:

<code class="language-sql">ALTER TABLE Thingies
ALTER COLUMN Name VARCHAR(25)
COLLATE Latin1_General_CS_AS</code>

This alteration ensures case-sensitive comparisons within both SQL and LINQ to Entities queries.

Application-Level (Client-Side) Workaround

If database modifications are impractical, a client-side solution can be implemented, though it's less performant:

<code class="language-csharp">Thingies.Where(t => t.Name == "ThingamaBob")
        .AsEnumerable()
        .First(t => t.Name == "ThingamaBob");</code>

This approach retrieves the data to the client, performing the case-sensitive comparison in memory.

Important Considerations

• Utilize ObjectQuery.ToTraceString() to examine the generated SQL and verify the collation being used.
• LINQ to Entities utilizes expression trees, processed by Object Services into command trees, and finally translated into database commands.
• Client-side case-sensitive comparisons can significantly impact performance compared to server-side solutions. Prefer the server-side method whenever possible.

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