What are the writing methods of MySQL commonly used SQL statements in MongoDB
MySQL commonly used SQL statements in the MongoDB which are written, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain in detail for you, people with this need can come to learn, I hope you can gain something.
If you have been using MySQL for a long time and are eager to try MongoDB, this simple article can help you get into character faster.
What are the common SQL statements of MySQL written in MongoDB?
Query:
MySQL:
SELECT * FROM user
Mongo:
Db.user.find ()
MySQL:
SELECT * FROM user WHERE name = 'starlee'
Mongo:
Db.user.find ({'name':' starlee'})
Insert:
MySQL:
INSERT INOT user (`name`, `age`) values ('starlee',25)
Mongo:
Db.user.insert ({'name':' starlee', 'age': 25})
ALTER TABLE user... .
But in MongoDB, all you need is:
Db.user.insert ({'name':' starlee', 'age': 25,' email': 'starlee@starlee.com'})
Delete:
MySQL:
DELETE * FROM user
Mongo:
Db.user.remove ({})
MySQL:
DELETE FROM user WHERE age
< 30 Mongo: db.user.remove({'age' : {$lt : 30}}) $gt : >; $gte: > =; $lt: <; $lte: 20
Mongo:
Db.user.distinct ('name', {' age': {$lt: 20}})
MySQL:
SELECT name, sum (marks) FROM user GROUP BY name
Mongo:
Db.user.group ({
Key: {'name': true}
Cond: {'name':' foo'}
Reduce: function (obj,prev) {prev.msum + = obj.marks;}
Initial: {msum: 0}
})
MySQL:
SELECT name FROM user WHERE age < 20 Mongo: db.user.find ('this.age < 20, {name: 1}) found that many people are searching for data inserted in the MongoDB loop. The following is the method of inserting data in the MongoDB loop: for (var iCompositi)
