Determining how a schema change occurred?
This gets logged to the default trace so, as long as it is enabled and hasn't rolled over in the meantime it should appear in the "Schema Changes History" report.

To access this in Management Studio right click the database then from the context menu choose Reports -&gt; Standard Reports -&gt; Schema Changes History

To retrieve the same information via TSQL you can use

SELECT StartTime
       ,LoginName
       --,f.*
FROM   sys.traces t
       CROSS APPLY fn_trace_gettable(REVERSE(SUBSTRING(REVERSE(t.path),
                                                       CHARINDEX('\', REVERSE(t.path)), 
                                                       260)
                                             ) + N'log.trc', DEFAULT) f
WHERE  t.is_default = 1
       AND ObjectName = 'FOO'
       AND EventClass IN (46, /*Object:Created*/
                          47, /*Object:Dropped*/
                          164 /*Object:Altered*/ )