最近剛剛學習完MySQL，現在又在學習Mongodb，都說語言是想通的，其實數據庫也是大同小異。在此做一個對比，方便小白用戶學習。(參考mongo的API)
1.名稱的區分
| MySQL | Mongodb |
| database（數據庫） | database（數據庫） |
| table（表格） | collection（集合） |
| row（行） | document（文檔） |
| column（列） | field（域） |
| index（索引） | index（索引） |
| table joins（聯表） | |
| primary key(主鍵),可以自定義 | primary key(主鍵)，一般是"_id" |
2.語法的區分
- 創建
MySQL Mongodb CREATE TABLE users ( id MEDIUMINT NOT NULL AUTO_INCREMENT, user_id Varchar(30), age Number, status char(1), PRIMARY KEY (id) )
db.users.insert( { user_id: "abc123", age: 55, status: "A" } )
或者是：db.createCollection("users")ALTER TABLE users ADD join_date DATETIME
db.users.update( { }, { $set: { join_date: new Date() } }, { multi: true } )
ALTER TABLE users DROP COLUMN join_date
db.users.update( { }, { $unset: { join_date: "" } }, { multi: true } )
CREATE INDEX idx_user_id_asc ON users(user_id)
db.users.createIndex( { user_id: 1 } )CREATE INDEX idx_user_id_asc_age_desc ON users(user_id, age DESC)
db.users.createIndex( { user_id: 1, age: -1 } )DROP TABLE users
db.users.drop() - 插入
MySQL Mongodb INSERT INTO users(user_id, age, status) VALUE("bcd001", 45, "A")
db.users.insert( { user_id: "bcd001", age: 45, status: "A" } )
- 查找
MySQL Mongodb SELECT * FROM users
db.users.find()SELECT id, user_id, status FROM users
db.users.find( { }, { user_id: 1, status: 1 } )
SELECT user_id, status FROM users
db.users.find( { }, { user_id: 1, status: 1, _id: 0 } )
SELECT * FROM users WHERE status = "A"
db.users.find( { status: "A" } )
SELECT user_id, status FROM users WHERE status = "A"
db.users.find( { status: "A" }, { user_id: 1, status: 1, _id: 0 } )
SELECT * FROM users WHERE status != "A"
db.users.find( { status: { $ne: "A" } } )
SELECT * FROM users WHERE status = "A" AND age = 50
db.users.find( { status: "A", age: 50 } )
SELECT * FROM users WHERE status = "A" OR age = 50
db.users.find( { $or: [ { status: "A" } , { age: 50 } ] } )
SELECT * FROM users WHERE age > 25
db.users.find( { age: { $gt: 25 } } )
SELECT * FROM users WHERE age < 25
db.users.find( { age: { $lt: 25 } } )
SELECT * FROM users WHERE age > 25 AND age <= 50
db.users.find( { age: { $gt: 25, $lte: 50 } } )
SELECT * FROM users WHERE user_id like "%bc%"
db.users.find( { user_id: /bc/ } )SELECT * FROM users WHERE user_id like "bc%"
db.users.find( { user_id: /^bc/ } )SELECT * FROM users WHERE status = "A"
ORDER BY user_id ASC
db.users.find( { status: "A" } ).sort( { user_id: 1 } )SELECT * FROM users WHERE status = "A" ORDER BY user_id DESC
db.users.find( { status: "A" } ).sort( { user_id: -1 } )SELECT COUNT(*) FROM users
db.users.count()或者
db.users.find().count()
SELECT COUNT(user_id) FROM users
db.users.count( { user_id: { $exists: true } } )or
db.users.find( { user_id: { $exists: true } } ).count()SELECT COUNT(*) FROM users WHERE age > 30
db.users.count( { age: { $gt: 30 } } )or
db.users.find( { age: { $gt: 30 } } ).count()SELECT DISTINCT(status) FROM users
db.users.distinct( "status" )SELECT * FROM users LIMIT 1
db.users.findOne()or
db.users.find().limit(1)SELECT * FROM users LIMIT 5 SKIP 10
db.users.find().limit(5).skip(10)EXPLAIN SELECT * FROM users WHERE status = "A"
db.users.find( { status: "A" } ).explain() - 更新
MySQL Mongodb UPDATE users SET status = "C" WHERE age > 25
db.users.update( { age: { $gt: 25 } }, { $set: { status: "C" } }, { multi: true } )
UPDATE users SET age = age + 3 WHERE status = "A"
db.users.update( { status: "A" } , { $inc: { age: 3 } }, { multi: true } )
- 刪除
MySQL Mongodb DELETE FROM users WHERE status = "D"
db.users.remove( { status: "D" } )DELETE FROM users
db.users.remove({})