一：插入
插入是向MongoDB中添加数据的基本方法
db.test.insert()
> use testdb switched to db testdb > db.test.insert({"name":"lile"}) WriteResult({"nInserted":1}) > db.test.findOne() {"_id":ObjectId("595f4e66f713ea7372854b9d"),"name":"lile"}
当想要一次性插入多个文档时，可以使用数组的形式db.test.insert([{},{},{}])
> db.test.insert([{"name":"ha"},{"name":"he"},{"name":"hei"}])
BulkWriteResult({
"writeErrors":[],
"writeConcernErrors":[],
"nInserted":3,
"nUpserted":0,
"nMatched":0,
"nModified":0,
"nRemoved":0,
"upserted":[]
})
> db.test.find() {"_id":ObjectId("595f4e66f713ea7372854b9d"),"name":"lile"} {"_id":ObjectId("595f52fff713ea7372854b9e"),"name":"ha"} {"_id":ObjectId("595f52fff713ea7372854b9f"),"name":"he"} {"_id":ObjectId("595f52fff713ea7372854ba0"),"name":"hei"}
还有很多关于insert的操作，如insertOne（）、insertMany（）等，官网：
二、删除
db.test.remove() 将会删除test集合中的所有文档
db.test.remove({"_id":ObjectId("595f4e66f713ea7372854b9d")}) 删除test集合中指定id号的文档
remove函数不会删除集合本身，也不会删除集合的元信息
若要删除集合，则使用drop函数，db.test.drop()把整个test集合给删掉，集合里的文档以及元数据都会删除，再用show tables查看时，不会再显示刚刚出现的集合
> db.test.drop() true > show tables; >
三、更新文档
文档插入数据库以后，就可以使用update方法来更新，update有两个参数，一个是查询文档，用于定位需要更新的目标文档；另一个是修改器（modifier）文档，用于说明要对找到的文档进行哪些修改。
更新操作是不可分割的：若是两个更新同时发生，先到达服务器的先执行，接着执行另一个。
1）文档替换 用一个新的文档完全替换匹配的文档
先插入一条数据
> db.user.insert({"name":"joe","friends":32,"enemies":2})
WriteResult({"nInserted":1})
> var joe = db.user.findOne({"name":"joe"}) //这里一定要这样findOne才行，find不行
> joe.relationship ={"friends":joe.friends,"enemies":joe.enemies};
{"friends":32,"enemies":2}
> delete joe.friends
true
> delete joe.enemies
true
> db.user.update({"_id":ObjectId("5962dde4530365edfecb4915")},joe)
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.user.findOne()
{
"_id":ObjectId("5962dde4530365edfecb4915"),
"name":"joe",
"relationship":{
"friends":32,
"enemies":2
}
}
2）使用修改器
通常文档只有一部分要更新。可以使用原子性的更改修改器（update modifier），指定对文档中的某些字段进行更新，更改修改器是种特殊的键，用来指定复杂的更新操作，比如修改、增加或者删除，还有可能是数组或者内嵌文档
例1：$inc
在一个集合中放置网站的分析数据，只要有人update，就使得页面的访问量加1，先在一个集合中插入文档
> db.web.insert({"url":"www.lile.com",pageviews:23})
WriteResult({"nInserted":1})
> db.web.findOne()
{
"_id":ObjectId("5962e533530365edfecb4917"),
"url":"www.lile.com",
"pageviews":23
}
> db.web.update({"url":"www.lile.com"},{"$inc":{pageviews:1}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
例2：$set
首先，插入一个文档
> db.user.insert({"name":"joe","age":30,"sex":"male"})
WriteResult({"nInserted":1})
再这个文档中，想要再添加喜欢的书籍进去：
> db.user.update({"_id":ObjectId("5962eaf9530365edfecb4918")},{"$set":{"favorite book":"war and peace"}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
过了一段时间，发现喜欢的是另一本书
> db.user.update({"_id":ObjectId("5962eaf9530365edfecb4918")},{"$set":{"favorite book":"Green hags and arm"}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.user.findOne()
{
"_id":ObjectId("5962eaf9530365edfecb4918"),
"name":"joe",
"age":30,
"sex":"male",
"favorite book":"Green hags and arm"
}
也可以喜欢多本书，用数组表示
> db.user.update({"_id":ObjectId("5962eaf9530365edfecb4918")},{"$set":{"favorite book":["war and peace","harbt"]}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.user.findOne()
{
"_id":ObjectId("5962eaf9530365edfecb4918"),
"name":"joe",
"age":30,
"sex":"male",
"favorite book":[
"war and peace",
"harbt"
]
}
例3： $unset
有一天突然发现自己不喜欢书了，可以删掉
> db.user.update({"_id":ObjectId("5962eaf9530365edfecb4918")},{"$unset":{"favorite book":1}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.user.findOne()
{
"_id":ObjectId("5962eaf9530365edfecb4918"),
"name":"joe",
"age":30,
"sex":"male"
}
$set 修改内嵌文档
首先，插入一个博客文档
> db.blog.insert({"title":"A blog Post","Content":"hahaha....","author":{"name":"joe","email":"lile@qq.com"}})
WriteResult({"nInserted":1})
> db.blog.findOne()
{
"_id":ObjectId("5962edc8530365edfecb4919"),
"title":"A blog Post",
"Content":"hahaha....",
"author":{
"name":"joe",
"email":"lile@qq.com"
}
}
名字弄错了，我想修改
> db.blog.update({"_id":ObjectId("5962edc8530365edfecb4919")},{"$set":{"author.name":"joe schome"}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.blog.findOne()
{
"_id":ObjectId("5962edc8530365edfecb4919"),
"title":"A blog Post",
"Content":"hahaha....",
"author":{
"name":"joe schome",
"email":"lile@qq.com"
}
}
例4：增加和减少 $inc
$inc 修改器用来增加已有键的值，或者键不存在就创建一个，用于分析数据，因果关系，投票或其他有变化数值的地方
假若建立一个游戏集合，将游戏和变化的分数都存在里面，每过关一次，增加50分
> db.game.insert({"game":"pinball","user":"joe"})
WriteResult({"nInserted":1})
> db.game.findOne()
{
"_id":ObjectId("5962ef3b530365edfecb491a"),
"game":"pinball",
"user":"joe"
}
> db.game.update({"_id":ObjectId("5962ef3b530365edfecb491a")},{"$inc":{"score":50}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.game.findOne()
{
"_id":ObjectId("5962ef3b530365edfecb491a"),
"game":"pinball",
"user":"joe",
"score":50
}
> db.game.update({"_id":ObjectId("5962ef3b530365edfecb491a")},{"$inc":{"score":50}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.game.findOne()
{
"_id":ObjectId("5962ef3b530365edfecb491a"),
"game":"pinball",
"user":"joe",
"score":100
}
$inc只能用于整形，长整型或双精度浮点型的值
3）：数组修改器 $push
在上面的博客系统中，要创建一个用于保存数组的comments评论键，$push会向已有的数组末尾加入一个元素，要是没有就创建一个新的数组。
> db.blog.update({"_id":ObjectId("5962edc8530365edfecb4919")},{"$push":{"comments":{"name":"lile","email":"lile.qq.com","content":"nice post"}}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.blog.findOne()
{
"_id":ObjectId("5962edc8530365edfecb4919"),
"title":"A blog Post",
"Content":"hahaha....",
"author":{
"name":"joe schome",
"email":"lile@qq.com"
},
"comments":[
{
"name":"lile",
"email":"lile.qq.com",
"content":"nice post"
}
]
}
若还想添加评论，可以继续使用$push，会在后面加一条评论数据
$ecah的用法，有一个个人的而基本信息，记录他的体重变化值
> db.math.insert({"name":"lile"})
WriteResult({"nInserted":1})
> db.math.findOne()
{"_id":ObjectId("5962f328530365edfecb491b"),"name":"lile"}
> db.math.update({"_id":ObjectId("5962f328530365edfecb491b")},{"$push":{"weight":{"$each":[{"month":58},{"Feb":60},{"Jun":62}]}}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.math.findOne()
{
"_id":ObjectId("5962f328530365edfecb491b"),
"name":"lile",
"weight":[
{
"month":58
},
{
"Feb":60
},
{
"Jun":62
}
]
}
$slice 限制插入数组的个数，$slice的值为负数，表示若插入的个数没有超过这个数，那么全部写入，若超过了，那么就取后面的个数
> db.math.update({"_id":ObjectId("5962f328530365edfecb491b")},{"$push":{"weight":{"$each":[23,45,6,6,67,45,24],"$slice":-3}}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.math.findOne()
{
"_id":ObjectId("5962f328530365edfecb491b"),
"name":"lile",
"weight":[
67,
45,
24
]
}
一个人的朋友信息，只允许写两个朋友，再写了多个的情况下，按年龄排序，取最后两个
> db.math.findOne() {"_id":ObjectId("5962f328530365edfecb491b"),"name":"lile"} > db.math.update({"_id":ObjectId("5962f328530365edfecb491b")},{"$push":{"friends":{"$each":[{"name":"lile","age":12},{"name":"xiaoming","age":34},{"name":"small red","age":23}],"$slice":-2,"$sort":{"age":1}}}}) WriteResult({"nMatched":1,"nUpserted":0,"nModified":1}) > db.math.findOne() { "_id":ObjectId("5962f328530365edfecb491b"), "name":"lile", "friends":[ { "name":"small red", "age":23 }, { "name":"xiaoming", "age":34 } ] }
例6：$addToSet
> db.users.update({"_id":ObjectId("59631989530365edfecb491c")},{"$addToSet":{"emails":"lile4.qq.com"}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
>
>
> db.users.findOne()
{
"_id":ObjectId("59631989530365edfecb491c"),
"name":"joe",
"emails":[
"lile.qq.com",
"lile2.qq.com",
"lile3.qq.com",
"lile4.qq.com"
]
}
$addToSet和$each一起使用，插入数组多个值
> db.users.update({"_id":ObjectId("59631989530365edfecb491c")},{"$addToSet":{"emails":{"$each":["lile5.qq.com","lile6.qq.com"]}}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.users.findOne()
{
"_id":ObjectId("59631989530365edfecb491c"),
"name":"joe",
"emails":[
"lile.qq.com",
"lile2.qq.com",
"lile3.qq.com",
"lile4.qq.com",
"lile5.qq.com",
"lile6.qq.com"
]
}
删除元素
有几个从数组中删除元素的方法。如果是把数组看成队列或者栈，可以使用$pop
这个修改器从数组任何一端删除元素{"$pop":{"key":1}} 从数组末尾删除一个元素
{"$pop":{"key":-1}} 从数组头部删除一个元素
例1：删除emails的第一个元素
> db.users.findOne() { "_id":ObjectId("59631989530365edfecb491c"), "name":"joe", "emails":[ "lile.qq.com", "lile2.qq.com", "lile3.qq.com", "lile4.qq.com", "lile5.qq.com", "lile6.qq.com" ] } > db.users.update({"_id":ObjectId("59631989530365edfecb491c")},{"$pop":{"emails":-1}}) WriteResult({"nMatched":1,"nUpserted":0,"nModified":1}) > db.users.findOne() { "_id":ObjectId("59631989530365edfecb491c"), "name":"joe", "emails":[ "lile2.qq.com", "lile3.qq.com", "lile4.qq.com", "lile5.qq.com", "lile6.qq.com" ] }
例2：数组中某个字段操作
原文是这样
> db.blog.findOne() { "_id":ObjectId("5962edc8530365edfecb4919"), "title":"A blog Post", "Content":"hahaha....", "comments":[ null, { "name":"lile", "email":"lile.qq.com", "content":"hahahhahahah post" }, { "name":"small red", "email":"lile.qq.com", "content":"This is bad blog" } ] }
删除comments数组中的第一个数值null
> db.blog.update({"comments.name":"lile"},{"$pop":{"comments":-1}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.blog.findOne()
{
"_id":ObjectId("5962edc8530365edfecb4919"),
"title":"A blog Post",
"Content":"hahaha....",
"comments":[
{
"name":"lile",
"email":"lile.qq.com",
"content":"hahahhahahah post"
},
{
"name":"lile",
"email":"lile.qq.com",
"content":"this is a bad blog"
}
]
}
然后我想在comments数组里，每一个值里添加一个字段votes，暂时只想到这种办法
> db.blog.findOne() { "_id":ObjectId("5962edc8530365edfecb4919"), "title":"A blog Post", "Content":"hahaha....", "comments":[ { "name":"lile", "email":"lile.qq.com", "content":"hahahhahahah post" }, { "name":"lile", "email":"lile.qq.com", "content":"this is a good blog" } ] } > db.blog.update({"_id":ObjectId("5962edc8530365edfecb4919")},{"$set":{"comments.0.votes":0}}) WriteResult({"nMatched":1,"nUpserted":0,"nModified":1}) > db.blog.findOne() { "_id":ObjectId("5962edc8530365edfecb4919"), "title":"A blog Post", "Content":"hahaha....", "comments":[ { "name":"lile", "email":"lile.qq.com", "content":"hahahhahahah post", "votes":0 }, { "name":"lile", "email":"lile.qq.com", "content":"this is a good blog" } ] } > db.blog.update({"_id":ObjectId("5962edc8530365edfecb4919")},{"$set":{"comments.1.votes":0}}) WriteResult({"nMatched":1,"nUpserted":0,"nModified":1}) > db.blog.findOne() { "_id":ObjectId("5962edc8530365edfecb4919"), "title":"A blog Post", "Content":"hahaha....", "comments":[ { "name":"lile", "email":"lile.qq.com", "content":"hahahhahahah post", "votes":0 }, { "name":"lile", "email":"lile.qq.com", "content":"this is a good blog", "votes":0 } ] }
删除刚刚添加的votes字段，只需把$set改为$unset即可
$用法，只会在第一个匹配的元素更新，而且做查询的时候必须是数组里的元素，不然会报错
这里是用_id号来匹配，报错
> db.blog.update({"comments.name":"lile"},{"$set":{"comments.$.votes":0}})
WriteResult({"nMatched":1,"nUpserted":0,"nModified":1})
> db.blog.findOne()
{
"_id":ObjectId("5962edc8530365edfecb4919"),
"title":"A blog Post",
"Content":"hahaha....",
"comments":[
{
"name":"lile",
"email":"lile.qq.com",
"content":"hahahhahahah post",
"votes":0
},
{
"name":"lile",
"email":"lile.qq.com",
"content":"this is a good blog"
}
]
}