学习mongo系列（五） AND,$or,$type

MongoDB OR 条件

MongoDB OR 条件语句使用了关键字 $or,语法格式如下：

>db.col.find(
   {
      $or: [
	     {key1: value1}, {key2:value2}
      ]
   }
).pretty()

> db.user.find({$or:[{"name":"admin","grade":"99"}]}).pretty()
> db.user.find({$or:[{"name":"admin","grade":"99"}]}).pretty()
> db.user.find({$or:[{"name":"admin"},{"grade":"99"}]}).pretty()
{
"_id" : ObjectId("56946fba3a18f4867aecbcd1"),
"name" : "admin",
"password" : "123456",
"title" : "admin",
"grade" : 50
}
> db.user.find({$or:[{{"grade":"99"},{"name":"admin"}]}).pretty()
...

没太明白$or的究竟

$type

MongoDB 中可以使用的类型如下表所示：

类型	数字	备注
Double	1
String	2
Object	3
Array	4
Binary data	5
Undefined	6	已废弃。
Object id	7
Boolean	8
Date	9
Null	10
Regular Expression	11
JavaScript	13
Symbol	14
JavaScript (with scope)	15
32-bit integer	16
Timestamp	17
64-bit integer	18
Min key	255	Query with -1.
Max key	127

我们使用的数据库名称为"maxh" 我们的集合名称为"user"，以下为我们插入的数据:

　　

> db.user.find().pretty()
{
"_id" : ObjectId("56946fba3a18f4867aecbcd1"),
"name" : "admin",
"password" : "123456",
"title" : "admin",
"grade" : 50
}
{
"_id" : ObjectId("5694714a3a18f4867aecbcd2"),
"name" : "aaaaaaaaa",
"password" : "123456",
"grade" : 99
}
{
"_id" : ObjectId("5694ce6685cf2632ea951c05"),
"name" : "xiaoniao",
"password" : "lijian",
"grade" : "15"
}

查找grade的类型为string(type = 2)类型的记录（行）

> db.user.find({"grade":{$type:2}}).pretty()
{
"_id" : ObjectId("5694ce6685cf2632ea951c05"),
"name" : "xiaoniao",
"password" : "lijian",
"grade" : "15"
}

查找grade的类型为double（数值type = 1）行的记录

> db.user.find({"grade":{$type:1}}).pretty()
{
"_id" : ObjectId("56946fba3a18f4867aecbcd1"),
"name" : "admin",
"password" : "123456",
"title" : "admin",
"grade" : 50
}
{
"_id" : ObjectId("5694714a3a18f4867aecbcd2"),
"name" : "aaaaaaaaa",
"password" : "123456",
"grade" : 99
}