关于使用MongoDB的强化练习

练习示例如下：

mongo

use test

首先准备一个集合的数据。

persons = [{
	name:"jim",
	age:25,
	email:"7543xx57@qq.com",
	c:89,m:96,e:87,
	country:"USA",
	books:["JS","C++","EXTJS","MONGODB"]
},
{
	name:"tom",
	age:25,
	email:"2145xx457@qq.com",
	c:75,m:66,e:97,
	country:"USA",
	books:["PHP","JAVA","EXTJS","C++"]
},
{
	name:"lili",
	age:26,
	email:"344xxx457@qq.com",
	c:75,m:63,e:97,
	country:"USA",
	books:["JS","JAVA","C#","MONGODB"]
},
{
	name:"zhangsan",
	age:27,
	email:"2xxx567457@qq.com",
	c:89,m:86,e:67,
	country:"China",
	books:["JS","JAVA","EXTJS","MONGODB"]
},
{
	name:"lisi",
	age:26,
	email:"27xx21457@qq.com",
	c:53,m:96,e:83,
	country:"China",
	books:["JS","C#","PHP","MONGODB"]
},
{
	name:"wangwu",
	age:27,
	email:"65xxx1457@qq.com",
	c:45,m:65,e:99,
	country:"China",
	books:["JS","JAVA","C++","MONGODB"]
},
{
	name:"zhaoliu",
	age:27,
	email:"21xxx1457@qq.com",
	c:99,m:96,e:97,
	country:"China",
	books:["JS","JAVA","EXTJS","PHP"]
},
{
	name:"piaoyingjun",
	age:26,
	email:"piaoyingjunx@uspcat.com",
	c:39,m:54,e:53,
	country:"Korea",
	books:["JS","C#","EXTJS","MONGODB"]
},
{
	name:"lizhenxian",
	age:27,
	email:"lizhenxianx@uspcat.com",
	c:35,m:56,e:47,
	country:"Korea",
	books:["JS","JAVA","EXTJS","MONGODB"]
},
{
	name:"lixiaoli",
	age:21,
	email:"lixiaolixx@uspcat.com",
	c:36,m:86,e:32,
	country:"Korea",
	books:["JS","JAVA","PHP","MONGODB"]
},
{
	name:"zhangsuying",
	age:22,
	email:"zhangsuyingxx@uspcat.com",
	c:45,m:63,e:77,
	country:"Korea",
	books:["JS","JAVA","C#","MONGODB"]
}]

将数据插入集合persons中

db.persons.insert(persons)
db.persons.find()

一、查询年龄大于25小于27的name，age

db.persons.find({age:{$gt:25,$lt:27}},{name:1,age:1,_id:0})

二、查询出country不是美国的name和country数据

①

db.persons.find({country:{$ne:"USA"}},{name:1,country:1,_id:0})

②

db.persons.find({country:{$nin:["USA"]}},{name:1,country:1,_id:0})

三、查询country是China或者USA的 name、age、country数据信息
①

db.persons.find({$or:[{country:{$eq:"USA"}},{country:{$eq:"China"}}]},{name:1,age:1,country:1,_id:0})

②

db.persons.find({country:{$in:["China","USA"]}},{name:1,age:1,country:1,_id:0})

四、查询语文（字段c）成绩大于85或者英语（字段e）成绩大于90的name、age、country、c、e数据信息

db.persons.find({$or:[{c:{$gt:85}},{e:{$gt:90}}]},{name:1,age:1,country:1,c:1,e:1,_id:0})

五、查询出名字中存在"li"的学生信息
这里使用了正则表达式

db.persons.find({name:/li/},{name:1,_id:0})

其中，两个斜杠/ 之间写的是正则表达式

拓展

• 不区分大小写 ：
  在斜杠后加一个小写字母i

db.persons.find({name:/li/i},{name:1,_id:0})

• 以某字符开头
  name以字符p开头为例

db.persons.find({name:/^p/},{name:1,_id:0})

• 以某字符结尾
  name以字符u结尾

db.persons.find({name:/u$/},{name:1,_id:0})

六、查询喜欢看MONGODB和PHP的学生

• 查找值为列表的字段，其列表中的元素

db.persons.find({books:{$all:["MONGODB","PHP"]}},{name:1,books:1,_id:0})

七、查询第二本书是JAVA的学生信息
即查询字段books的列表中第二个元素为JAVA的人

db.persons.find({"books.1":"JAVA"},{name:1,books:1,_id:0})

"books.1"表示books的第二个元素，索引从0开始计数。

• 拓展
  向books列表中添加一个元素
  向name为jim的数据的books的列表中添加一个元素"HADOOP"。

db.persons.update({name:"jim"},{$push:{books:"HADOOP"}})

向name为jim的数据的books的列表中添加多个元素"SPARK"，“HBASE”。

db.persons.update({name:"jim"},{$push:{books:{$each:["SPARK","HBASE"]}}})

八、查询喜欢的书数量是4本的学生

db.persons.find({books:{$size: 4}},{name:1,books:1,_id:0})

九、查询出persons中的国家分别是什么

db.persons.distinct("country")

如果想查看长度：

db.persons.distinct("country").length