01.增删改查

1.1 插入数据

• 1.插入文档: insert 如果插入数据的时候，collection还不存在，自动创建集合
• 2.insertOne: 插入一条数据
• 3.insertMany: 接收数组，插入多条文档

#1、插入单条数据
db.student1.insertOne({_id:"stu001","name":"Tom","age":25,grade:{"chinese":80,"math":90,"english":88}})

#2、插入多条数据
db.student1.insertMany([
  {_id:"stu002","name":"Mary","age":23,grade:{"chinese":80,"math":90}},
  {_id:"stu003","name":"Mike","age":23,grade:{"chinese":81,"math":90,"english":88}}
]);

1.2 更新文档

• updateOne和updateMany

#1、更新_id=7839的薪水 ---> 8000
db.emp.updateOne({"_id":7839},{$set:{"sal":8000}})
db.emp.find({"_id":7839})  # 查询id=7893的文档

#2、更新多条数据：更新10号部门的员工薪水，加100块钱
错误：db.emp.updateMany({"deptno":{$eq:10}},{$set:{"sal":"sal"+100}})  ---> 不对
正确：db.emp.updateMany({"deptno":{$eq:10}},{$inc:{"sal",100}})

1.3 删除文档

• deleteOne和deleteMany

db.emp.deleteOne({"_id":7839})

1.4 批处理

• 注: 为了提高效率，db.collection.bulkWrite，支持：insert update remove 同时也支持insertMany

db.mystudents.bulkWrite([
  {insertOne:{"document":{"_id":100,"name":"Tom","age":25}}},
  {insertOne:{"document":{"_id":101,"name":"Mary","age":24}}},
  {updateOne:{"filter":{"_id":100},"update":{$set:{"name":"Tom123"}}}}
]);