Implement an internal-note update without selecting the whole order first.

• Use this only when existing state is not needed for validation or authorization.
• Mark exactly one property modified.
• Handle a zero-row update deliberately.
• Do not overwrite other fields with stub defaults.

I attach a stub containing only the key, assign the allowed field, and mark that property modified. EF then generates a narrow update. This is not a default replacement for loading aggregates; it is a deliberate optimization for a command whose invariant can be enforced without current entity state.

public static async Task<bool> UpdateInternalNoteAsync(
    AppDbContext db,
    Guid orderId,
    string note,
    CancellationToken cancellationToken)
{
    var order = new Order { Id = orderId };
    db.Attach(order);

    order.InternalNote = note.Trim();
    db.Entry(order)
        .Property(candidate => candidate.InternalNote)
        .IsModified = true;

    try
    {
        await db.SaveChangesAsync(cancellationToken);
        return true;
    }
    catch (DbUpdateConcurrencyException)
    {
        return false;
    }
}

The database receives one narrow update and no preceding select. EF expects one affected row and can surface a zero-row update as DbUpdateConcurrencyException. If the model has required concurrency tokens, those original values must also be supplied or this pattern should not be used.

• The order id does not exist.
• The note becomes empty after trimming.
• A concurrency token is configured on the entity.
• A tracked order with the same key already exists in the context.

• Inspect generated SQL and confirm only the intended column changes.
• Test the missing-row result.
• Verify authorization occurs before this method.
• Reject use when business rules depend on current order state.

• Marking the whole stub entity modified and overwriting columns with defaults.
• Using the pattern when domain rules need existing values.
• Ignoring configured concurrency tokens.
• Attaching a duplicate key into a context already tracking that entity.