MongoDB Learning Notes

Mongodb Learning

Installation-level configuration Windows random boot

1. Download MongoDB and unzip to D:\database\mongodb\mongo

2. Configure environment Variables

1. new environment variable mongo_home=d:\database\mongodb\mongo\bin

2. Add the path variable %mongo_home%;

3. Configure the database installation and log folders

1. Add the logs and data folders under the D:\database\mongodb folder

2. Add mongodb.log files under the logs folder

4. Configuring Windows boot- up

Enter mongod--dbpath D:\database\mongodb\data--logpath=d:\database\mongodb\logs\mongodb.log--install on the command line

5. test whether the installation is successful

Enter MONGO on the command line to indicate that the installation was successful

Basic operations

Add Action Db.person.insert ({"Name": "Tom", "Age": +})

Find operations

Find all db.person.find ()

Conditional Query db.person.find ({"Name": "Tom"})

>,>=,<,<=,!=,= corresponding to "$gt", "$gte", "$lt", "$lte", "$ne", " no special keywords "

>:d b.person.find ({"Age", {$gt: 20}})

<:d B.person.find ({"Age", {$lt: 20}})

=:d B.person.find ({"Age", 20})

And,or,in,notin " No keywords", "$or", "$in","$nin" respectively

And:db.person.find ({"Name": "Tom", "Age": 20})

Or:db.person.find ({$or: [{"Name": "Tom"},{"name": "Zhangsan"}]})

In:db.person.find ({"name": {$in: ["Zhangsan", "Tom"]}})

NotIn:db.person.find ({"Name", {$nin: ["Zhangsan", "Tom"]}})

Regular Expression db.person.find ({"Name":/^j/, "name":/e$/})

$where Db.person.find ({$where: function () {return this.name== "Tom"}})

Query number of records in the person collection db.person.count ()

Modify Operation

Overall modified db.person.update ({"Name", "Tom"},{"name": "Tom1", "Age":-})

Local modifications

$inc add increase abbreviation db.person.update ({"Name", "Tom"},{$inc: {"Age": +})// tom.age=40 after modification

$set Set db.person.update ({"Name": "Tom"},{$set: {"Age": +})// modified tom.age=20

Inserupdate Mode

Insert a new data if no data is found based on the first query condition

Db.person.update ({"Name": "Tom1"},{$set: {"age": 40}},true)

Batch Modification

MongoDB Default if you find more than one piece of data to modify based on a single query condition, only one is modified by default, and you can set the fourth parameter to true for bulk modification

Delete Operation Db.person.remove ({"Name": "Tom1"})

Aggregation operations

Count Total Records Db.person.count ()

Number of records in condition Db.person.count ({"Age": {$gt: +}})

Distinct db.person.distinct ("name") without conditions

Conditional de- db.person.distinct ("name", {"age": {$gt: +}})

Group Basic Group

Db.person.group ({"key": {"name": true}, "initial": {"person": []}, "Reduce": function (doc,out) {Out.person.push ( Doc.name+ ":" +doc.age)})

Show the number of each group

Db.person.group ({"key": {"Age": true}, "initial": {"person": []}, "Reduce": function (doc,out) {Out.person.push ( Doc.name+ ":" +doc.age)}, "Finalize": function (out) {out.count=out.person.length}})

Grouping with conditions

Db.person.group ({"key": {"Age": true}, "initial": {"person": []}, "Reduce": function (doc,out) {Out.person.push ( Doc.name+ ":" +doc.age)}, "Finalize": function (out) {out.count=out.person.length}, "condition": {"age": {$gt: 30}})

Mapreduce

First step: Create a mapping function

var map=function () {Emit (This.age,{count:1})}// grouping parameters

Step two: Create a simplified function

var reduce=function (key,value) {var result={count:0};    for (Var i=0;i<value.length;i++) {Result.count+=value[i].count; } return result; }

Step three: Execute the function

Db.person.mapReduce (map,reduce,{"Out": "Collection"})

Index operations

Build an index

Db.person.ensureIndex ({"Name": 1})//Add index to name field 1 for ascending order,1 the index that is established by default on behalf of descending order is not a unique index

Create a unique index

Db.person.ensureIndex ({"Name": 1},{"unique": true})

Set up a composite index

Db.person.ensureIndex ({"Name": 1, "Age":-1})

Gets the index index under the collection

Db.person.getIndexes ()

Delete Index

Db.person.dropIndex ({"Name": 1})

MongoDB Learning Notes