title: Update an entity in ef core w/o querying it specifying the alternate key?
body: <p>I want to update an entity (without requesting it) by just specifying the alternateKey. Is this possible?</p>
  
  <pre><code>using (var db = GetContext())
  using (var transaction = db.Database.BeginTransaction())
  {
      // [...]
  
      var status = new ImportStatus();
      status.ID = 201;  // don't know the real PK. With PK it works!
      status.Symbol = symbol; // this is the alternateKey
      status.DateLastImport = DateTime.Now;
  
      db.Attach(status);
      db.Entry(status).Property("DateLastImport").IsModified = true;
  
      await db.SaveChangesAsync(cancellationToken);
      await transaction.CommitAsync(cancellationToken);
  }
  </code></pre>