MongoDB-从对象内的数组中查找数据

我的数据库格式如下

{
"_id" : ObjectId("56fc92adcf908c9f296e5885"),
"_class" : "com.abc.ppm.dto.AccessAttemptDTO",
"url" : "/myProject/edit",
"ipAddress" : "127.0.0.1",
"param" : {
    "iecode" : [ 
        "P1234"
    ],
    "id" : [ 
        "5696578c6d34f835dc632fdd "
    ]
},
"accessTime" : "30-3-2016 10:59:57",
"email" : "abc@gmail.com",
"entity" : "admin",
"entityCode" : ""
},

{
"_id" : ObjectId("56fc92adcf908c9f296e5887"),
"_class" : "com.abc.ppm.dto.AccessAttemptDTO",
"url" : "/myProject/edit",
"ipAddress" : "127.0.0.1",
"param" : {
    "iecode" : [ 
        "P1122"
    ],
    "id" : [ 
        "5696578c6d34f835dc632fdd "
    ]
},
"accessTime" : "30-3-2016 10:59:57",
"email" : "abc@gmail.com",
"entity" : "admin",
"entityCode" : ""

}

---

现在我想找到所有的enries，其中iecode是'P1234'。我该怎么做？（注意：iecodes值以字符串数组格式存储。）

您可以编写如下查询：

db.collectionName.find({"param.iecode": "P1234"})