The following query worked for me until last Thursday (Aug 29, 2013). On Thursday, it continued working for most symbols that I have tried EXCEPT for SPY.
SELECT * FROM yahoo.finance.option_contracts WHERE symbol="SPY"
What has changed that SPY doesn't work?
The following url ALSO fails which suggests that the problem is on the server.
Has anyone else experienced this problem? Can someone at Y! take a look?