Linq returning unexpected results

Question

I have the following query which should return no rows, but returns 4:

var testAgainst = db.MyForm1_hosps.Select(ta => ta.recordId == recordId);

If I use the following query I get zero rows as expected:

var testAgainst = from ta in db.MyForm1_hosps where ta.recordId == recordId select ta;

There ARE four rows in MyForm1_hosp but none match the recordId in my test.

The code doesn't lie, so my understanding of LINQ is incorrect. Can someone explain to me why the first one returns 4 rows when it should return 0?

db.MyForm1_hosps.Where(ta => ta.recordId == recordId);

L.B
– L.B

2012-02-20 16:56:12 +00:00
Commented Feb 20, 2012 at 16:56 — L.B
– L.B, Commented Feb 20, 2012 at 16:56

Anthony Pegram · Accepted Answer · 2012-02-20 16:55:56Z

Your first query has a mistake. Change the Select to Where.

var testAgainst = db.MyForm1_hosps.Where(ta => ta.recordId == recordId);

Investigating your original query with Select(ta => ta.recordId == recordId): This will return a sequence of booleans. If none of the records in db.MyForm1_hosps have recordId values matching the input, the results will all be false. If you have 4 records, you will get 4 false values. You have 4 results, but they are not of the type you think they are!

derp derp, that is what i get for using a method based solely on its name. thanks for the explanation and change suggestion.

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