mongodb 简单的CRUD
CRUD练习笔记: Create(增加): 增加一个users表的集合: db.createCollection("users") 往users添加BJON数据 db.users.insert({name:"sue",age:36,status:"A",groups:["news","sports"]}) db.users.insert({name:"jim",age:18,status:"B",groups:["news","sports"]}) db.users.insert({name:"lily",age:32,status:"C",groups:["news","sports"]}) 翻译成sql: insert into user (name,age,status) values ("sue","26","A") Read(查询/读): 查看集合的内容 db.users.find() 在MongoDB中查看内容可以指定条件 db.user.find({age:{$gt:18}},{name:1,age:1}).limit(5) 翻译成sql: select _id,name,age from users where age>18 limit 5 还可以写成这样(按age来进行升序排序,如果是1的话就升序,如果是-1的话就降序,limit(5)限制只能查出5条数据): db.users.find({age:{$gt:18}},{name:1,age:1}).limit(5).sort({age:1}) 如果查询的时候想排除某个字段,将1改成0,可以这样写: db.users.find({age:{$gt:18}},{_id:0,name:1,age:1}).limit(5).sort({age:1}) Update(更新): 1)db.user.update({age:32},{$set:{status:"c"}}) 2)db.user.update({age:{$gt:32}},{$set:{status:"c"}}) 翻译成sql: 1) update user set status='A' where age=32 2) update user set status='A' where age>32 需要注意的是:这样也只是更新一条数据,必须添加{multi:true}才能实现多行更新 应该写成: db.user.update({age:{$gt:32}},{$set:{status:"c"}},{multi:true}) Delete(删除): db.user.remove( {status:"D"}) 翻译成sql: delete from user where status='D'