MongoDB vs. mysql command in detail _mongodb

The traditional relational database is generally composed of three levels of database, table, records (record), MongoDB are made up of three levels of databases (database), Collections (collection), document objects (documents)。 MongoDB for tables in relational databases, but there is no column, row, and relationship concept in the collection, which embodies the characteristics of pattern freedom.

Mysql	Mongodb	Description
Mysqld	Mongod	Server daemon
Mysql	Mongo	Client Tools
Mysqldump	Mongodump	Logical Backup tool
Mysql	Mongorestore	Logical Recovery Tool
	Db.repairdatabase ()	Repairing the database
Mysqldump	Mongoexport	Data Export Tool
Source	Mongoimport	Data Import Tool
Grant * privileges on *.* to ...	Db.adduser () Db.auth ()	New User and Permissions
Show databases	Show DBS	Show Library List
Show tables	Show collections	Show Table List
Show slave status	Rs.status	Query master-Slave status
Create table Users (a int, b int)	Db.createcollection ("Mycoll", {capped:true, size:100000}) Another: The table can be created implicitly.	Create a table
Create INDEX idxname on users (name)	Db.users.ensureIndex ({name:1})	Create an index
Create INDEX idxname on users (Name,ts DESC)	Db.users.ensureIndex ({name:1,ts:-1})	Create an index
Insert into users values (1, 1)	Db.users.insert ({a:1, b:1})	Insert Record
Select A, B from users	Db.users.find ({},{a:1, b:1})	Query table
Select * from users	Db.users.find ()	Query table
Select * from users where age=33	Db.users.find ({age:33})	Conditional query
Select A, b from users where age=33	Db.users.find ({age:33},{a:1, b:1})	Conditional query
SELECT * from Users where age<33	Db.users.find ({' age ': {$lt: 33}})	Conditional query
SELECT * from users where age>33 and age<=40	Db.users.find ({' age ': {$gt: $lte: 40}})	Conditional query
SELECT * from users where a=1 and b= ' Q '	Db.users.find ({a:1,b: ' Q '})	Conditional query
SELECT * from users where a=1 or b=2	Db.users.find ({$or: [{a:1}, {b:2}]})	Conditional query
SELECT * from users limit 1	Db.users.findOne ()	Conditional query
SELECT * from the users where name like "%joe%"	Db.users.find ({name:/joe/})	Fuzzy query
SELECT * from the users where name like "joe%"	Db.users.find ({name:/^joe/})	Fuzzy query
Select COUNT (1) from users	Db.users.count ()	Get the number of table records
Select COUNT (1) from the users where age>30	Db.users.find ({age: {' $gt ':}}). Count ()	Get the number of table records
Select DISTINCT last_name from Users	Db.users.distinct (' last_name ')	Remove duplicate values
SELECT * from users ' ORDER by name	Db.users.find (). Sort ({name:-1})	Sort
SELECT * from users ' ORDER by name DESC	Db.users.find (). Sort ({name:-1})	Sort
EXPLAIN SELECT * from Users where z=3	Db.users.find ({Z:3}). Explain ()	Get Storage Path
Update users set a=1 where b= ' Q '	Db.users.update ({b: ' Q '}, {$set: {a:1}}, False, True)	Update records
Update users set a=a+2 where b= ' Q '	Db.users.update ({b: ' Q '}, {$inc: {a:2}}, False, True)	Update records
Delete from users where z= "abc"	Db.users.remove ({z: ' abc '})	Delete a record
	Db. Users.remove ()	Delete all records
Drop database IF EXISTS test;	Use test Db.dropdatabase ()	Delete Database
drop table IF EXISTS test;	Db.mytable.drop ()	Delete Table/collection
	Db.adduser (' Test ', ' test ')	Add user Readonly-->false
	Db.adduser (' Test ', ' test ', true)	Add user Readonly-->true
	Db.adduser ("Test", "test222")	Change Password
	Db.system.users.remove ({User: "Test"}) or Db.removeuser (' test ')	Delete User
	Use admin	Super User
	Db.auth (' Test ', ' test ')	User authorization
	Db.system.users.find ()	View the list of users
	Show Users	View All Users
	Db.printcollectionstats ()	View the status of each collection
	Db.printreplicationinfo ()	View Master-slave replication status
	Show profile	View Profiling
	Db.copydatabase (' mail_addr ', ' mail_addr_tmp ')	Copy Database
	Db.users.dataSize ()	To view the size of collection data
	Db. Users.totalindexsize ()	Size of query Index

MongoDB Syntax
MongoDB the advantages of a lot of, such as multiple-column index, query can use some statistical functions, support for multiple conditions query, but the current multiple table query is not supported, you can find ways to solve the problem of multiple table query data redundancy.
MongoDB has a lot to do with data, and here's a few examples, mostly from official documents and partly for your own understanding.

Query Colls all data
Db.colls.find ()//select * from Colls
Query by specifying criteria
Db.colls.find ({' last_name ': ' Smith '});//select * from Colls where last_name= ' Smith '
Specifying a multiple-condition query
Db.colls.find ({x:3, y: "foo"});//select * from Colls where x=3 and y= ' foo '

Specify criteria range Query
Db.colls.find ({j: {$ne: 3}, K: {$gt: a});//select * from Colls where j!=3 and k>10

The query does not include a content
Db.colls.find ({}, {a:0});//query for all data except a 0

Support for, <=, ", >= query, need to replace the symbol for $LT, $lte, $GT, $gte
Db.colls.find ({"field": {$gt: Value}});
Db.colls.find ({"field": {$lt: Value}});
Db.colls.find ({"field": {$gte: Value}});
Db.colls.find ({"field": {$lte: Value}});

You can also do a range query on a field
Db.colls.find ({"field": {$gt: value1, $lt: value2}});

is not equal to the character $ne for the query
Db.colls.find ({x: {$ne: 3}});

In Query character $in
Db.colls.find ({"field": {$in: Array}});
Db.colls.find ({j:{$in: [2,4,6]}});

Not in query character $nin
Db.colls.find ({j:{$nin: [2,4,6]}});

Character $mod for modulo query
Db.colls.find ({A: {$mod: [1]}})/where a% 10 = 1

$all Query
Db.colls.find ({A: {$all: [2, 3]}});//Specifies that a satisfies any value in the array

$size Query
Db.colls.find ({A: {$size: 1}});//To query the number of objects, this query queries a record of the number of child objects of a 1

$exists Query
Db.colls.find ({A: {$exists: true}}); Data exists for object a
Db.colls.find ({A: {$exists: false}}); No data exists for object a

$type query $type value is the type value of bsonhttp://bsonspec.org/data
Db.colls.find ({A: {$type: 2}}); Match A is a string type of data
Db.colls.find ({A: {$type: 16}}); Match A is type int data

Using regular expression matching
Db.colls.find ({name:/acme.*corp/i});//similar to SQL

Inline Object Query
Db.colls.find ({"Author.name": "Joe"});

1.3.3 version and later version contains $not query
Db.colls.find ({name: {$not:/acme.*corp/i}});
Db.colls.find ({A: {$not: {$mod: [10, 1]}});

Sort () sorting
Db.colls.find (). Sort ({ts:-1});//1 for ascending 2 in descending order

Limit () to limit the number of query data returned
Db.colls.find (). Limit (10)

Skip () Skip some data
Db.colls.find (). Skip (10)

Snapshot () snapshot guarantees no duplicate data return or object loss

Count () to Count query objects
Db.students.find ({' address.state ': ' CA '}). Count ();//High efficiency
Db.students.find ({' address.state ': ' CA '}). ToArray (). length;//Inefficient

Group () is a grouping of query results similar to the group by function in SQL
Distinct () returns a value that is not repeated