【3】MongoDB对MySQL常用的SQL语句对应的实现

MongoDB对MySQL常用的SQL语句对应的实现
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MySQL:
SELECT * FROM user
Mongo:
db.user.find()
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MySQl:
SELECT * FROM user WHERE name = 'foobar'
Mongo:
db.user.find({ 'name' : 'foobar' })
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MySql:
INSERT INTO user ('name','age') VALUES ('foobar',25)
Mongo:
db.user.insert({ 'name' : 'foobar' , 'age' : 25})
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如果想增加email这一列
MySql:
ALTER TABLE user ...
Mongo:
db.user.insert({ 'name' : 'foobar' , 'age' : 25 , 'email' : '[e-mail]' })
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MySql:
DELETE * FROM user
Mongo:
db.user.remove({})
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MySql:
DELETE FROM user WHERE age < 30
Mongo:
db.user.remove({ 'age' : {$lt : 30}})
$gt:> ; $gte:>= ; $lt:< ; $lte:<= ; $ne:!=
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MySql:
UPDATE user SET `age` = 36 WHERE `name` = 'foobar'
Mongo:
db.user.update({ 'name' : 'foobar'} , {$set : { 'age' : 36}})
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MySQL:
UPDATE user SET `age` = 'age' + 3 WHERE `name` = 'foobar'
Mongo:
db.user.update({ 'name' : 'foobar'} , {$inc : {'age' : 3}})
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MySQl:
SELECT COUNT(*) FROM user WHERE `name` = 'foobar'
Mongo:
db.user.find({ 'name' : 'foobar'}).count()
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MySql:
SELECT * FROM user limit 10,20
Mongo:
db.user.find().skip(10).limit(20)
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MySQl:
SELECT * FROM user WHERE `age` IN (25,35,45)
Mongo:
db.user.find({ 'age' : {$in : [25,35,45]}})
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MySql:
SELECT * FROM user ORDER BY age DESC
Mongo:
db.user.find().sort({ 'age' : -1})
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MySQL:
SELECT DISTINCT(name) FROM user WHERE age > 20
Mongo:
db.user.distinct( 'name',{'age' : {$lt : 20}})
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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}
})
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MySQL:
SELECT name FROM user WHERE age < 20
Mongo:
db.user.find('this.age < 20' , {name : 1})