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.net - Select new records by timestamp column with Entity Framework

I have a table with timestamp column (RowId) in my SQL Server database.

I want to query new rows according to this timestamp. The SQL query is following

SELECT *
 FROM [MyTable]
 where RowId>=0x0000000000A99B06

0x0000000000A99B06 is a max timestamp value from the previous query.

How can I make such a query using Entity Framework database-first? RowId maps to byte[] property and I have no idea how to compare byte arrays in a LINQ query.

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1 Answer

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by (71.8m points)

Actually you can do small hack. It works for me 100%

internal static class EntityFrameworkHelper
{
   public static int Compare(this byte[] b1, byte[] b2)
   {
      throw new NotImplementedException();
   }  
}

And after that you can use it like this:

public void SomeMethod()
{
   var messages = Set<Message>().Where(m => m.Modified.Compare(filter.TimeStamp) > 0).ToList();
}

It will eventually generate SQL syntax like this: "Select * from Messages Where Modified > @param). And it works. Exception is never thrown.


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