MongoDB 匹配查詢和比較操作符

一、匹配查詢

1. 查詢所有

> 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. 查詢所有+展示美化

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

3. 查詢特定字段

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

4. 查詢主鍵

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

二、使用比較操作符

操作符	說明
eq	等於
ne	不等於
gt	大於
gte	大於等於
lt	小於
lte	小於等於

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