mysql 和 mongo db 语法对比

查询

MySQL: 
SELECT * FROM user 
Mongo: 
db.user.find() 
MySQL: 
SELECT * FROM user WHERE name = ’starlee’ 
Mongo: 
db.user.find({‘name’ : ’starlee’}) 

插入

MySQL: 
INSERT INOT user (`name`, `age`) values (’starlee’,25) 
Mongo: 
db.user.insert({‘name’ : ’starlee’, ‘age’ : 25}) 
在MySQL里添加一个字段： 
ALTER TABLE user…. 
在MongoDB里添加一个字段： 
db.user.insert({‘name’ : ’starlee’, ‘age’ : 25, ‘email’ : ’starlee@starlee.com’}) 

删除

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 : <= ; $ne : != 

更新

MySQL: 
UPDATE user SET `age` = 36 WHERE `name` = ’starlee’ 
Mongo: 
db.user.update({‘name’ : ’starlee’}, {$set : {‘age’ : 36}}) 
MySQL: 
UPDATE user SET `age` = `age` + 3 WHERE `name` = ’starlee’ 
Mongo: 
db.user.update({‘name’ : ’starlee’}, {$inc : {‘age’ : 3}}) 
MySQL: 
SELECT COUNT(*) FROM user WHERE `name` = ’starlee’ 
Mongo: 
db.user.find({‘name’ : ’starlee’}).count() 
MySQL: 
SELECT * FROM user limit 10,20 
Mongo: 
db.user.find().skip(10).limit(20) 
MySQL: 
SELECT * FROM user WHERE `age` IN (25, 35,45) 
Mongo: 
db.user.find({‘age’ : {$in : [25, 35, 45]}}) 
MySQL: 
SELECT * FROM user ORDER BY age DESC 
Mongo: 
db.user.find().sort({‘age’ : -1}) 
MySQL: 
SELECT DISTINCT(name) FROM user WHERE age > 20 
Mongo: 
db.user.distinct(‘name’, {‘age’: {$lt : 20}}) 
MySQL: 
SELECT name, sum(marks) FROM user where name='foo' 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}) 

循环插入数据

for(var i=0;i<100;i++)db.test.insert({uid:i,uname:’nosqlfan’+i}); 
上面一次性插入一百条数据，大概结构如下： 
{ “_id” : ObjectId(“4c876e519e86023a30dde6b8″), “uid” : 55, “uname” : “nosqlfan55″ } 
{ “_id” : ObjectId(“4c876e519e86023a30dde6b9″), “uid” : 56, “uname” : “nosqlfan56″ } 
{ “_id” : ObjectId(“4c876e519e86023a30dde6ba”), “uid” : 57, “uname” : “nosqlfan57″ } 
{ “_id” : ObjectId(“4c876e519e86023a30dde6bb”), “uid” : 58, “uname” : “nosqlfan58″ } 
{ “_id” : ObjectId(“4c876e519e86023a30dde6bc”), “uid” : 59, “uname” : “nosqlfan59″ } 
{ “_id” : ObjectId(“4c876e519e86023a30dde6bd”), “uid” : 60, “uname” : “nosqlfan60″ }