如果數(shù)據(jù)庫中尚未有數(shù)據(jù), 準備測試數(shù)據(jù)
db.test1.insertMany([ ????{"name":"zhangsan","age":19,"score": [90,80]}, ????{"name":"lisi","age":29,"score": [40,60]}, ????{"name":"xiaoming","age":18,"score": [20,40]}, ????{"name":"xiaohong"} ])
第一部分元素操作符
1.$exists: 判斷指定字段是否存在,并返回相應的結(jié)果2.$type: 匹配字段對應的類型
1.1$exists
{field: { $exists: } }
判斷指定字段是否存在,并返回相應的結(jié)果, 直接上代碼
{"$exists": true}
> db.test1.find({"qty": {"$exists":true}})#張三存在qty屬性, 就返回該條數(shù)據(jù){"_id": ObjectId("58c8dc54ef9b994487420f29"),"name":"zhangsan","age": 19,"score": [ 90, 80 ],"qty": 10 }
{"$exists": false}
> db.test1.find({"qty": {"$exists":false}})#以下三條數(shù)據(jù)均不存在qty字段{"_id": ObjectId("58c8dc54ef9b994487420f2a"),"name":"lisi","age": 29,"score": [ 40, 60 ] } {"_id": ObjectId("58c8dc54ef9b994487420f2b"),"name":"xiaoming","age": 18,"score": [ 20, 40 ] } {"_id": ObjectId("58c9e4b80c4d4cf6f4563b26"),"name":"xiaohong"}
1.2 $type
{field: { $type: | } }
第二部分
1.$mod模運算2.$regex ???正則表達3.$text ???文本搜索4.$where: 支持js表達式
2.1 $mod運算
db.users.find('this.age % 6 == 0'); ?或者 ?> db.users.find({"age": {$mod : [6,0]}}); {"_id": ObjectId("58d21667edca14f0f7ffbedb"),"name":"xiaoming","age":18,"score": [20,40] }
2.2 $regex正則表達
注: 之后后專門整理一篇正則表達式的文章
2.3 $text
2.4 where
