样例数据：
{
"_id" : "1064621564857",
"cNo" : "1064621564857",
"exPCodes" : [
{
"pType" : NumberInt(1),
"cDate" : ISODate("2017-07-27T10:30:11.783+0800")
}
]
}
{
"_id" : "1064621565572",
"cNo" : "1064621565572",
"exPCodes" : [
{
"pType" : NumberLong(3),
"cDate" : ISODate("2017-08-25T12:06:08.278+0800")
}
]
}
{
"_id" : "1064621565721",
"cNo" : "1064621565721",
"exPCodes" : [
{
"pType" : NumberLong(2),
"cDate" : ISODate("2017-07-14T14:44:00.522+0800")
}
]
}
查询 exPCodes的cDate是2017-07月份的，且pType等于1的：
{ "exPCodes": { $elemMatch: { cDate: { $gte: ISODate("2017-07-01T00:00:00.000+0800"), $lte: ISODate("2017-07-31T00:00:00.000+0800") },pType:1} } }