python-mongodb基本操作都在这了

数据库
    增
        use db1 #有则切换，无则新增

    查
        show dbs #查看所有
        db #当前

    删
        db.dropDatabase()

集合：
    增:
        db.user
        db.user.info
        db.user.auth

    查看
        show collections
        show tables

     删
        db.user.info.drop()

文档：
    增
        db.user.insert({"_id":1,"name":"egon"})
        user0={
            "name":"egon",
            "age":10,
            'hobbies':['music','read','dancing'],
            'addr':{
                'country':'China',
                'city':'BJ'
            }
        }

        db.user.insert(user0)
        db.user.insertMany([user1,user2,user3,user4,user5])

        db.t1.insert({"_id":1,"a":1,"b":2,"c":3})
        #有相同的_id则覆盖，无相同的_id则新增，必须指定_id
        db.t1.save({"_id":1,"z":6})
        db.t1.save({"_id":2,"z":6})
        db.t1.save({"z":6})

　　　　　save与insert的区别:
       　　 若新增的数据中存在主键 ，insert() 会提示错误，而save() 则更改原来的内容为新内容。
       　　 如：
    　　　　 已存在数据：  {_id : 1, " name " : " n1 " }，再次进行插入操作时，
    　　　　 insert({_id : 1, " name " : " n2 " })    会报主键重复的错误提示
    　　　　 save({ _id : 1, " name " : " n2 " })     会把 n1 修改为  n2  。
    　　　　 相同点：
    　　　　 若新增的数据中没有主键时，会增加一条记录。
    　　　　 已存在数据：  { _id : 1, " name " : " n1 " }，再次进行插入操作时，
    　　　　 insert({ " name " : " n2 " })    插入的数据因为没有主键，所以会增加一条数据
    　　　　 save({  " name " : " n2 " })   增加一条数据。
    查

        比较运算：=，!=,>,<,>=,<=
        #1、select * from db1.user where id = 3
        db.user.find({"_id":3})

        #2、select * from db1.user where id != 3
        db.user.find({"_id":{"$ne":3}})

        #3、select * from db1.user where id > 3
        db.user.find({"_id":{"$gt":3}})

        #4、select * from db1.user where age < 3
        db.user.find({"age":{"$lt":3}})

        #5、select * from db1.user where id >= 3
        db.user.find({"_id":{"$gte":3}})

        #6、select * from db1.user where id <= 3
        db.user.find({"_id":{"$lte":3}})


        #逻辑运算:$and,$or,$not
        #1 select * from db1.user where id >=3 and id <=4;
        db.user.find({"_id":{"$gte":3,"$lte":4}})

        #2 select * from db1.user where id >=3 and id <=4 and age >=40;
        db.user.find({
            "_id":{"$gte":3,"$lte":4},
            "age":{"$gte":40}
        })

        db.user.find({"$and":[
        {"_id":{"$gte":3,"$lte":4}},
        {"age":{"$gte":40}}
        ]})


        #3 select * from db1.user where id >=0 and id <=1 or id >=4 or name = "yuanhao";
        db.user.find({"$or":[
        {"_id":{"$lte":1,"$gte":0}},
        {"_id":{"$gte":4}},
        {"name":"yuanhao"}
        ]})

        #4 select * from db1.user where id % 2 = 1;
        db.user.find({"_id":{"$mod":[2,1]}})


        db.user.find({
            "_id":{"$not":{"$mod":[2,1]}}
        })

        #成员运算:$in,$nin
        db.user.find({"name":{"$in":["alex","egon"]}})
        db.user.find({"name":{"$nin":["alex","egon"]}})


        #正则匹配
        select * from db1.user where name regexp "^jin.*?(g|n)$";
        db.user.find({
            "name":/^jin.*?(g|n)$/i
        })


        #查看指定字段
        select name,age from db1.user where name regexp "^jin.*?(g|n)$";
        db.user.find({
            "name":/^jin.*?(g|n)$/i
        },
        {
            "_id":0,
            "name":1,
            "age":1
        }
        )

        #查询数组相关
        db.user.find({
            "hobbies":"dancing"
        })

        db.user.find({
            "hobbies":{"$all":["dancing","tea"]}
        })

        db.user.find({
            "hobbies.2":"dancing"
        })

        db.user.find(
        {},
        {
            "_id":0,
            "name":0,
            "age":0,
            "addr":0,
            "hobbies":{"$slice":[1,2]},
        }
        )


        db.user.find(
        {},
        {
            "_id":0,
            "name":0,
            "age":0,
            "addr":0,
            "hobbies":{"$slice":2},
        }
        )


        db.user.find(
        {
            "addr.country":"China"
        }
        )

        db.user.find().sort({"_id":1,"age":-1})


        db.user.find().limit(2).skip(0)
        db.user.find().limit(2).skip(2)
        db.user.find().limit(2).skip(4)
        db.user.find().distinct()
        
    改
        一 语法：
            db.table.update(
            条件,
            修改字段,
            其他参数
            )

            update db1.t1 set id=10 where name="egon";

            db.table.update(
            {},
            {"age":11},
            {
                "multi":true,
                "upsert":true
            }
            )

            1、update db1.user set age=23,name="武大郎" where name="wupeiqi";
            #覆盖式
            db.user.update(
                {"name":"wupeiqi"},
                {"age":23,"name":"武大郎"}
            )
            #局部修改:$set
            db.user.update(
                {"name":"alex"},
                {"$set":{"age":73,"name":"潘金莲-alex"}}
            )

            #改多条
            db.user.update(
                {"_id":{"$gte":1,"$lte":2}},
                {"$set":{"age":53,}},
                {"multi":true}
            )
            #有则修改，无则添加
            db.user.update(
                {"name":"EGON"},
                {"$set":{"name":"EGON","age":28,}},
                {"multi":true,"upsert":true}
            )

            #修改嵌套文档
            db.user.update(
                {"name":"潘金莲-alex"},
                {"$set":{"addr.country":"Japan"}}
            )

            #修改数组
            db.user.update(
                {"name":"潘金莲-alex"},
                {"$set":{"hobbies.1":"Piao"}}
            )

            #删除字段
            db.user.update(
                {"name":"潘金莲-alex"},
                {"$unset":{"hobbies":""}}
            )

            2、$inc
            db.user.update(
                {},
                {"$inc":{"age":1}},
                {"multi":true}
            )

            db.user.update(
                {},
                {"$inc":{"age":-10}},
                {"multi":true}
            )

            3、$push, $pop  $pull
            db.user.update(
                {"name":"yuanhao"},
                {"$push":{"hobbies":"tangtou"}},
                {"multi":true}
            )

            db.user.update(
                {"name":"yuanhao"},
                {"$push":{"hobbies":{"$each":["纹身","抽烟"]}}},
                {"multi":true}
            )

            #从头删-1，从尾删1
            db.user.update(
                {"name":"yuanhao"},
                {"$pop":{"hobbies":-1}},
                {"multi":true}
            )

            db.user.update(
                {"name":"yuanhao"},
                {"$pop":{"hobbies":1}},
                {"multi":true}
            )

            #按条件删
            db.user.update(
                {"name":"yuanhao"},
                {"$pull":{"hobbies":"纹身"}},
                {"multi":true}
            )

            #3、$addToSet
            db.t3.insert({"urls":[]})
            db.t3.update(
                {},
                {"$addToSet":{"urls":{"$each":[
                    "http://www.baidu.com",
                    "http://www.baidu.com",
                    "http://www.baidu.com",
                    "http://www.baidu.com",
                    "http://www.baidu.com"
                ]}}},
                {"multi":true}
            )


    删
        db.user.deleteOne({"_id":{"$gte":3}})
        db.user.deleteMany({"_id":{"$gte":3}})
        db.user.deleteMany({})

        
    聚合
        一：$match
            例：
                select post from db1.emp where age > 20 group by post having avg(salary) > 10000;

            #$match
            #1、select * from db1.emp where age > 20
            db.emp.aggregate({"$match":{"age":{"$gt":20}}})

            #$group
            #2、select post from db1.emp where age > 20 group by post;
            db.emp.aggregate(
                {"$match":{"age":{"$gt":20}}},
                {"$group":{"_id":"$post"}}
            )

            #3、select post,avg(salary) as avg_salary from db1.emp where age > 20 group by post;
            db.emp.aggregate(
                {"$match":{"age":{"$gt":20}}},
                {"$group":{"_id":"$post","avg_salary":{"$avg":"$salary"}}}
            )

            #select post from db1.emp where age > 20 group by post having avg(salary) > 10000;
            db.emp.aggregate(
                {"$match":{"age":{"$gt":20}}},
                {"$group":{"_id":"$post","avg_salary":{"$avg":"$salary"}}},
                {"$match":{"avg_salary":{"$gt":10000}}}
            )

        二： 投射
　　　　　　      {"$project":{"要保留的字段名":1,"要去掉的字段名":0,"新增的字段名":"表达式"}}
            例1：
            db.emp.aggregate(
                {"$project":{"_id":0,"name":1,"post":1,"annual_salary":{"$multiply":[12,"$salary"]}}},
                {"$group":{"_id":"$post","平均年薪":{"$avg":"$annual_salary"}}},
                {"$match":{"平均年薪":{"$gt":1000000}}},
                {"$project":{"部门名":"$_id","平均年薪":1,"_id":0}}
            )

            例2：
            db.emp.aggregate(
                {"$project":{"_id":0,"name":1,"hire_period":{"$subtract":[new Date(),"$hire_date"]}}}
            )


            db.emp.aggregate(
                {"$project":{"_id":0,"name":1,"hire_year":{"$year":"$hire_date"}}}
            )

            db.emp.aggregate(
                {"$project":{"_id":0,"name":1,"hire_period":{"$subtract":[{"$year":new Date()},{"$year":"$hire_date"}]}}}
            )

            例3：
            db.emp.aggregate(
                {"$project":{"_id":0,"new_name":{"$toUpper":"$name"},}}
            )

            db.emp.aggregate(
                {"$match":{"name":{"$ne":"egon"}}},
                {"$project":{"_id":0,"new_name":{"$concat":["$name","_SB"]},}}
            )

            db.emp.aggregate(
                {"$match":{"name":{"$ne":"egon"}}},
                {"$project":{"_id":0,"new_name":{"$substr":["$name",0,3]},}}
            )

        三：{"$group":{"_id":分组字段,"新的字段名":聚合操作符}}

            #select post,max,min,sum,avg,count,group_concat from db1.emp group by post;

            db.emp.aggregate(
                {"$group":{
                    "_id":"$post",
                    "max_age":{"$max":"$age"},
                    "min_id":{"$min":"$_id"},
                    "avg_salary":{"$avg":"$salary"},
                    "sum_salary":{"$sum":"$salary"},
                    "count":{"$sum":1},
                    "names":{"$push":"$name"}
                    }
                }
            )


        四：排序：$sort、限制：$limit、跳过：$skip
            db.emp.aggregate(
                {"$match":{"name":{"$ne":"egon"}}},
                {"$project":{"_id":1,"new_name":{"$substr":["$name",0,3]},"age":1}},
                {"$sort":{"age":1,"_id":-1}},
                {"$skip":5},
                {"$limit":5}
            )


        # 补充
        db.emp.aggregate({"$sample":{"size":3}})   #随机选取3个文档