select month(date()),stats[0].year sts from baseball group by sts having sts=1904  

--empty result set

--program sends wrong aggregate command: 

--[ { "$project" : { "month(date())" : { "$month" : ISODate('2013-09-30T12:22:02.066Z') }, "sts" : 1 } }, { "$group" : { "_id" : '$stats.0.year' } }, { "$project" : { "_id" : 0, "sts" : '$_id' } }, { "$project" : { "month(date())" : { "$month" : ISODate('2013-09-30T12:22:02.066Z') }, "_id" : 1, "sts" : 1 } }, { "$match" : { "sts" : 1904 } } ]

go

 

--without aliases works correct