MongoDB笔记(四) 查询操作(详细)
查询操作(详细)
1.查询集合所有文档
2.等值条件查询
3.嵌套文档查询
4.数组查询
5.查找null值字段，查找指定无值字段
6.或条件查找
7.查询操作符
8.正则表达式
9.区间查询
1.查询集合所有文档
db.goodstest.find() //goodstest:collection name
db.goodstest.find().pretty()> db.goodstest.find()
{ "_id" : ObjectId("60744b754a2bf7c4568674b5"), "name" : "《C语言》", "price" : 33.2, "adddate" : "2020-10-1", "allow" : true, "baseinf" : { "ISBN" : 1838388, "press" : "清华大学出版社" }, "tags" : [ "good", "book", "it", "program" ] }
{ "_id" : ObjectId("60744d964a2bf7c4568674b8"), "name" : "《c program》", "price" : 45 }
{ "_id" : 2222, "toy" : null }
{ "_id" : 1112 }
> db.goodstest.find().pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}
{
"_id" : ObjectId("60744d964a2bf7c4568674b8"),
"name" : "《c program》",
"price" : 45
}
{ "_id" : 2222, "toy" : null }
{ "_id" : 1112 }2.等值条件查询
> db.goodstest.find({name:"《c program》"})
{ "_id" : ObjectId("60744d964a2bf7c4568674b8"), "name" : "《c program》", "price" : 45 }
> db.goodstest.find(
... {name:"《c program》"},
... {name:1,price:1,_id:0} //1表示显示，0表示不显示
... )
{ "name" : "《c program》", "price" : 45 }3.嵌套文档查询
> db.goodstest.find({"baseinf.press":"清华大学出版社"})
{ "_id" : ObjectId("60744b754a2bf7c4568674b5"), "name" : "《C语言》", "price" : 33.2, "adddate" : "2020-10-1", "allow" : true, "baseinf" : { "ISBN" : 1838388, "press" : "清华大学出版社" }, "tags" : [ "good", "book", "it", "program" ] }
> db.goodstest.find({baseinf.press:"清华大学出版社"})
2021-04-12T22:38:00.826+0800 E QUERY [thread1] SyntaxError: missing : after property id @(shell):1:26 //注意baseinf.press要加双引号4.数组查询
> db.goodstest.find({tags:["good","book","it","program"]}).pretty()
> db.goodstest.find({tags:"good"}).pretty()
> db.goodstest.find({tags:{$size:4}}).pretty()> db.goodstest.find({tags:["good","book","it","program"]}).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}
> db.goodstest.find({tags:"good"}).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}
> db.goodstest.find({tags:{$size:4}}).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}5.查找null值字段，查找指定无值字段
> db.goodstest.find({_id:2222,toy:null})
{ "_id" : 2222, "toy" : null }
> db.goodstest.find({_id:1112,toy:{$exists:false}})
{ "_id" : 1112 }6.或条件查找
> db.goodstest.find({price:{$in:[33,33.2]}}).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}7.查询操作符
小于和小于等于（<和<=）：
> db.goodstest.find({price:{$lt:45}}).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}
> db.goodstest.find({price:{$lte:45}}).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}
{
"_id" : ObjectId("60744d964a2bf7c4568674b8"),
"name" : "《c program》",
"price" : 45
}大于和大于等于（>和>=）：
> db.goodstest.find({price:{$gt:33.2}}).pretty()
{
"_id" : ObjectId("60744d964a2bf7c4568674b8"),
"name" : "《c program》",
"price" : 45
}
> db.goodstest.find({price:{$gte:33.2}}).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}
{
"_id" : ObjectId("60744d964a2bf7c4568674b8"),
"name" : "《c program》",
"price" : 45
}不等于（!=）：
> db.goodstest.find({price:{$ne:33.2}}).pretty()
{
"_id" : ObjectId("60744d964a2bf7c4568674b8"),
"name" : "《c program》",
"price" : 45
}
{ "_id" : 2222, "toy" : null }
{ "_id" : 1112 }与：
> db.goodstest.find({price:{$ne:33.2},name:"《c program》"}).pretty()
{
"_id" : ObjectId("60744d964a2bf7c4568674b8"),
"name" : "《c program》",
"price" : 45
}或：
> db.goodstest.find({$or:[{price:45},{_id:2222}]}).pretty()
{
"_id" : ObjectId("60744d964a2bf7c4568674b8"),
"name" : "《c program》",
"price" : 45
}
{ "_id" : 2222, "toy" : null }8.正则表达式
:{$regex:/patten/ patten:
/^查询的值/ ：查询值的前面部分固定 相当于“查询的值%”
/查询的值$/ ：查询值的后面部分固定 相当于“%查询的值”
/查询的值/ ：查询所有包含查询的值的文档 相当于“%查询的值%”
option：
i ：不区分大小写字母
> db.goodstest.find().pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}
{
"_id" : ObjectId("60744d964a2bf7c4568674b8"),
"name" : "《c program》",
"price" : 45
}
{
"_id" : ObjectId("6079579e0f65fbc098679fa3"),
"name" : "《c语言》",
"price" : 28
}
> db.goodstest.find({name:{$regex:/^《c/}}).pretty()
{
"_id" : ObjectId("60744d964a2bf7c4568674b8"),
"name" : "《c program》",
"price" : 45
}
{
"_id" : ObjectId("6079579e0f65fbc098679fa3"),
"name" : "《c语言》",
"price" : 28
}
> db.goodstest.find({name:{$regex:/语言》$/}}).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}
{
"_id" : ObjectId("6079579e0f65fbc098679fa3"),
"name" : "《c语言》",
"price" : 28
}
加入option参数和不加option参数的区别：
> db.goodstest.find({name:{$regex:/C语/}}).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}
> db.goodstest.find({name:{$regex:/C语/i}}).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}
{
"_id" : ObjectId("6079579e0f65fbc098679fa3"),
"name" : "《c语言》",
"price" : 28
}9.区间查询
> db.goodstest.find({price:{$gt:30,$lt:40}}).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}10.limit和skip方法
limit()函数用于限制查询结果的个数，若匹配不到括号里数量的结果，则返回匹配数量的结果
> db.goodstest.find().limit(2).pretty()
{
"_id" : ObjectId("60744b754a2bf7c4568674b5"),
"name" : "《C语言》",
"price" : 33.2,
"adddate" : "2020-10-1",
"allow" : true,
"baseinf" : {
"ISBN" : 1838388,
"press" : "清华大学出版社"
},
"tags" : [
"good",
"book",
"it",
"program"
]
}
{
"_id" : ObjectId("60744d964a2bf7c4568674b8"),
"name" : "《c program》",
"price" : 45
}skip()函数用于略过指定个数的文档
> db.goodstest.find().skip(2).pretty()
{
"_id" : ObjectId("6079579e0f65fbc098679fa3"),
"name" : "《c语言》",
"price" : 28
}下一篇：MongoDB笔记(五) 更新操作(详细)