MongoDB学习第七篇 --- sql和mongodb对比

一、术语和概念的对比

SQL	MongoDB
database	database
row	document or BSON document
column	field
index	index
table joins	$lookup, embedded documents
primary key Specify any unique column or column combination as primary key.	primary key In MongoDB, the primary key is automatically set to the _id field.
aggregation (e.g. group by)	aggregation pipeline

二、对库和表的操作语句对比

SQL	MongoDB
CREATE TABLE people ( id MEDIUMINT NOT NULL AUTO_INCREMENT, user_id Varchar(30), age Number, status char(1), PRIMARY KEY (id) )	直接执行insert操作即可，如果表不存在，自动创建 db.people.insertOne( { user_id: "abc123", age: 55, status: "A" } ) 也可以用一下语句创建collection db.createCollection("people")
ALTER TABLE people ADD join_date DATETIME	db.people.updateMany( { }, { $set: { join_date: new Date() } } )
ALTER TABLE people DROP COLUMN join_date	db.people.updateMany( { }, { $unset: { "join_date": "" } } )
CREATE INDEX idx_user_id_asc ON people(user_id)	db.people.createIndex( { user_id: 1 } )
CREATE INDEX idx_user_id_asc_age_desc ON people(user_id, age DESC)	db.people.createIndex( { user_id: 1, age: -1 } )
DROP TABLE people	db.people.drop()

三、insert语句的对比

SQL INSERT Statements	MongoDB insertOne() Statements
INSERT INTO people(user_id, age, status) VALUES ("bcd001", 45, "A")	db.people.insertOne( { user_id: "bcd001", age: 45, status: "A" } )

四、select语句的对比

SQL SELECT Statements	MongoDB find() Statements
SELECT * FROM people	db.people.find()
SELECT id, user_id, status FROM people	db.people.find( { }, { user_id: 1, status: 1 } )
SELECT user_id, status FROM people	db.people.find( { }, { user_id: 1, status: 1, _id: 0 } )
SELECT * FROM people WHERE status = "A"	db.people.find( { status: "A" } )
SELECT user_id, status FROM people WHERE status = "A"	db.people.find( { status: "A" }, { user_id: 1, status: 1, _id: 0 } )
SELECT * FROM people WHERE status != "A"	db.people.find( { status: { $ne: "A" } } )
SELECT * FROM people WHERE status = "A" AND age = 50	db.people.find( { status: "A", age: 50 } )
SELECT * FROM people WHERE status = "A" OR age = 50	db.people.find( { $or: [ { status: "A" } , { age: 50 } ] } )
SELECT * FROM people WHERE age > 25	db.people.find( { age: { $gt: 25 } } )
SELECT * FROM people WHERE age < 25	db.people.find( { age: { $lt: 25 } } )
SELECT * FROM people WHERE age > 25 AND age <= 50	db.people.find( { age: { $gt: 25, $lte: 50 } } )
SELECT * FROM people WHERE user_id like "%bc%"	db.people.find( { user_id: /bc/ } ) -or- db.people.find( { user_id: { $regex: /bc/ } } )
SELECT * FROM people WHERE user_id like "bc%"	db.people.find( { user_id: /^bc/ } ) -or- db.people.find( { user_id: { $regex: /^bc/ } } )
SELECT * FROM people WHERE status = "A" ORDER BY user_id ASC	db.people.find( { status: "A" } ).sort( { user_id: 1 } )
SELECT * FROM people WHERE status = "A" ORDER BY user_id DESC	db.people.find( { status: "A" } ).sort( { user_id: -1 } )
SELECT COUNT(*) FROM people	db.people.count() or db.people.find().count()
SELECT COUNT(user_id) FROM people	db.people.count( { user_id: { $exists: true } } ) or db.people.find( { user_id: { $exists: true } } ).count()
SELECT COUNT(*) FROM people WHERE age > 30	db.people.count( { age: { $gt: 30 } } ) or db.people.find( { age: { $gt: 30 } } ).count()
SELECT DISTINCT(status) FROM people	db.people.distinct( "status" )
SELECT * FROM people LIMIT 1	db.people.findOne() or db.people.find().limit(1)
SELECT * FROM people LIMIT 5 SKIP 10	db.people.find().limit(5).skip(10)
EXPLAIN SELECT * FROM people WHERE status = "A"	db.people.find( { status: "A" } ).explain()

五、update语句的对比

SQL Update Statements	MongoDB updateMany() Statements
UPDATE people SET status = "C" WHERE age > 25	db.people.updateMany( { age: { $gt: 25 } }, { $set: { status: "C" } } )
UPDATE people SET age = age + 3 WHERE status = "A"	db.people.updateMany( { status: "A" } , { $inc: { age: 3 } } )

六、delete语句的对比

SQL Delete Statements	MongoDB deleteMany() Statements
DELETE FROM people WHERE status = "D"	db.people.deleteMany( { status: "D" } )
DELETE FROM people	db.people.deleteMany({})