Code sometimes work and sometimes does not

[wiki-me]

In the last section and the last question.

When i enter this code:

SELECT DISTINCT c1.cosponsor_name FROM cosponsors c1 LEFT JOIN cosponsors CS2 ON c1.sponsor_name = CS2.cosponsor_name WHERE CS2.cosponsor_name IS NULL

Sometimes it shows:

No data returned

Other times it seems to work correctly (showing "Correct" a few seconds after showing the resulting table).

It seems to me that the code should work always, or at least give a deterministic result. You might have to try 10-20 times to see it is giving out different results.

[zichongkao]

Interesting. The non-determinism makes me wonder if the sqlite DB is timing out. After all, that query is one of the more expensive ones. Let me see if it's possible to reduce the data size!