MongoDB 匹配查询和比较操作符

一、匹配查询

1. 查询所有

> db.accounts.find()
{ "_id" : "account1", "name" : "alice", "balance" : 100 }
{ "_id" : ObjectId("5d7f25f4aecbd2bc0fa821b3"), "name" : "charlie", "balance" : 500 }
{ "_id" : ObjectId("5d7f25f4aecbd2bc0fa821b4"), "name" : "david", "balance" : 200 }
{ "_id" : { "name" : "david", "balance" : 200 }, "name" : "charlie", "balance" : 500 }
{ "_id" : { "balance" : 200, "name" : "david" }, "name" : "charlie", "balance" : 500 }
{ "_id" : { "balance" : "200", "name" : "david" }, "name" : "charlie", "balance" : 500 }

2. 查询所有+展示美化

> db.accounts.find().pretty()

3. 查询特定字段

> db.accounts.find({"name":"alice2"}).pretty()
{ "_id" : "account1", "name" : "alice2", "balance" : 100 }
{
 "_id" : ObjectId("5d7f43abaecbd2bc0fa821b7"),
 "name" : "alice2",
 "balance" : 100
}

4. 查询主键

> db.accounts.find({"_id.name":"david"}).pretty()
{
 "_id" : {
  "name" : "david",
  "balance" : 200
 },
 "name" : "charlie",
 "balance" : 500
}

二、使用比较操作符

操作符	说明
eq	等于
ne	不等于
gt	大于
gte	大于等于
lt	小于
lte	小于等于

> db.accounts.find({"balance":{$lt:200}}).pretty()
{ "_id" : "account1", "name" : "alice2", "balance" : 100 }
{
 "_id" : ObjectId("5d7f43abaecbd2bc0fa821b7"),
 "name" : "alice2",
 "balance" : 100
}