第三部分
1.$all: 匹配数组中包含query中的元素2.$elemMatch : 筛选数组中的元素3.$size: 匹配数组中元素的个数.
3.1$all
{: { $all:[,... ] } }
官方实例
{tags:{ $all:["ssl","security"] } } 等价于 { $and: [ {tags:"ssl"}, {tags:"security"} ] }
为了便于理解, 在此修改一下测试数据, 将小明的成绩改为三个数字
> db.users.update({"name":"xiaoming"}, {"$push": {"score":100}})WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
此时两种成功的筛选数据的方式, 得到结果
#测试数据在最上边,必须同时满足score包含备选数据, [子集与真子集] > db.users.find({"score": {"$all": [20,40]}}) {"_id": ObjectId("58d21667edca14f0f7ffbedb"),"name":"xiaoming","age":18,"score": [20,40,100] } > db.users.find({"score": {"$all": [20,40,100]}}) {"_id": ObjectId("58d21667edca14f0f7ffbedb"),"name":"xiaoming","age":18,"score": [20,40,100] }
无结果数据
#没有任何一条数据的score**同时**包含2060> db.users.find({"score": {"$all": [20,60]}}) >
总结X$in 与 $all的区别
用实例告诉大家的区别
x.1$in原始数据中只要包含一条或多条备选数据,即满足
> db.users.find({"score": {"$in": [20,60]}}) {"_id": ObjectId("58d21667edca14f0f7ffbeda"),"name":"lisi","age":29,"score": [40,60] } {"_id": ObjectId("58d21667edca14f0f7ffbedb"),"name":"xiaoming","age":18,"score": [20,40,100] }
x.2 $all原始数据必须完整的包含或等于被选数据
#为空 > db.users.find({"score": {"$all": [20,60]}}) >
3.2 $elemMatch
语法
{: {$elemMatch: {,, ... } } }
实例一
筛选数组中包含大于50小于100的数据,只要属于其子集即可
> db.users.find({"score": {"$elemMatch": {"$gt":50,"$lt":100}}}) {"_id": ObjectId("58d21667edca14f0f7ffbed9"),"name":"zhangsan","age":19,"score": [90,80] } {"_id": ObjectId("58d21667edca14f0f7ffbeda"),"name":"lisi","age":29,"score": [40,60] }
实例二
插入测试数据
db.test1.insert([ {"id":1,"results": [ {"product":"abc","score":10}, {"product":"xyz","score":5} ] }, {"id":2,"results": [ {"product":"abc","score":8}, {"product":"xyz","score":7} ] }, {"id":3,"results": [ {"product":"abc","score":7}, {"product":"xyz","score":8} ] } ])
定位其中的一条
> db.test1.find({"results": {"$elemMatch": {"product":"abc","score": {"$gt":8}}}}) {"_id": ObjectId("58d26383fc8d60106f1885bc"),"id":1,"results": [ {"product":"abc","score":10}, {"product":"xyz","score":5} ] } >
3.3 $size:匹配数组中元素的个数.
筛选score拥有三个子集的数据
> db.users.find({"score": {"$size":3}}) {"_id": ObjectId("58d21667edca14f0f7ffbedb"),"name":"xiaoming","age":18,"score": [20,40,100] }
第四部分基本操作符
插入测试数据
> for(vari =0; i < 100; i++){db.test2.insert({"age": i}) } WriteResult({"nInserted":1}) > db.test2.find().count()100
4.1 Skip()
语法
>db.COLLECTION_NAME.find().limit(NUMBER).skip(NUMBER)
官方实例
functionprintStudents(pageNumber, nPerPage){print("Page: "+ pageNumber); db.students.find().skip(pageNumber >0? ((pageNumber-1)*nPerPage) :0).limit(nPerPage).forEach(function(student){print(student.name +"
"); } ); }
> db.test2.find().skip(95) {"_id":ObjectId("58d26dc1b527dc1a130563a8"),"age": 95 } {"_id":ObjectId("58d26dc1b527dc1a130563a9"),"age": 96 } {"_id":ObjectId("58d26dc1b527dc1a130563aa"),"age": 97 } {"_id":ObjectId("58d26dc1b527dc1a130563ab"),"age": 98 } {"_id":ObjectId("58d26dc1b527dc1a130563ac"),"age": 99 }
4.2排序sort()
默认为升序[1], 降序为[-1]
>db.COLLECTION_NAME.find().sort({KEY:1}) >
例子
#默认升序 > db.test2.find().sort({"age":1}) {"_id":ObjectId("58d26dc1b527dc1a13056349"),"age": 0 } {"_id":ObjectId("58d26dc1b527dc1a1305634a"),"age": 1 } {"_id":ObjectId("58d26dc1b527dc1a1305634b"),"age": 2 } {"_id":ObjectId("58d26dc1b527dc1a1305634c"),"age": 3 } {"_id":ObjectId("58d26dc1b527dc1a1305634d"),"age": 4 } #降序 > db.test2.find().sort({"age": -1}) {"_id":ObjectId("58d26dc1b527dc1a130563ac"),"age": 99 } {"_id":ObjectId("58d26dc1b527dc1a130563ab"),"age": 98 } {"_id":ObjectId("58d26dc1b527dc1a130563aa"),"age": 97 } {"_id":ObjectId("58d26dc1b527dc1a130563a9"),"age": 96 }
4.2排序limit()
>db.COLLECTION_NAME.find().limit(NUMBER)
> db.test2.find().limit(5) {"_id":ObjectId("58d26dc1b527dc1a13056349"),"age": 0 } {"_id":ObjectId("58d26dc1b527dc1a1305634a"),"age": 1 } {"_id":ObjectId("58d26dc1b527dc1a1305634b"),"age": 2 } {"_id":ObjectId("58d26dc1b527dc1a1305634c"),"age": 3 } {"_id":ObjectId("58d26dc1b527dc1a1305634d"),"age": 4 }
4.3综上一块来个实例
放在一块说会好些, 要不没有说明性
跳过前10条, 显示接下来的5条, 并按照age升序排列
> db.test2.find().skip(10).sort({"age":1}).limit(5) {"_id":ObjectId("58d26dc1b527dc1a13056353"),"age": 10 } {"_id":ObjectId("58d26dc1b527dc1a13056354"),"age": 11 } {"_id":ObjectId("58d26dc1b527dc1a13056355"),"age": 12 } {"_id":ObjectId("58d26dc1b527dc1a13056356"),"age": 13 } {"_id":ObjectId("58d26dc1b527dc1a13056357"),"age": 14 }
