MongoDB的基本操作
使用 insert 完成插入操作
操作格式: db.<集合>.insertOne(<json对象>) db.<集合>.insertMany([, , …])
> db.fruit.insertOne({name: "apple"}) 插入的语句 返回信息 { "acknowledged" : true, "insertedId" : ObjectId("5e980a7e05d499f414a4e839") } >db.fruit.insertMany([ {name: "apple"}, {name: "pear"}, {name: "orange"} ... ]) 插入的语句 返回信息 { "acknowledged" : true, "insertedIds" : [ ObjectId("5e980a8205d499f414a4e83a"), ObjectId("5e980a8205d499f414a4e83b"), ObjectId("5e980a8205d499f414a4e83c") ] }
查看插入的数据
> db.fruit.find() { "_id" : ObjectId("5e980a7e05d499f414a4e839"), "name" : "apple" } { "_id" : ObjectId("5e980a8205d499f414a4e83a"), "name" : "apple" } { "_id" : ObjectId("5e980a8205d499f414a4e83b"), "name" : "pear" } { "_id" : ObjectId("5e980a8205d499f414a4e83c"), "name" : "orange" } { "_id" : ObjectId("5e980a8b05d499f414a4e83d"), "name" : "apple" }
关于 find: find 是 MongoDB 中查询数据的基本指令,相当于 SQL 中的 SELECT 。 find 返回的是游标
find 示例:
db.fruit.find( { "name" : "apple" } ) #只有一个条件的查询 { "_id" : ObjectId("5e980a7e05d499f414a4e839"), "name" : "apple" } { "_id" : ObjectId("5e980a8205d499f414a4e83a"), "name" : "apple" } { "_id" : ObjectId("5e980a8b05d499f414a4e83d"), "name" : "apple" } > db.fruit.find( { "name" : "apple","_id" : ObjectId("5e980a8b05d499f414a4e83d") } ) #多条件并存and { "_id" : ObjectId("5e980a8b05d499f414a4e83d"), "name" : "apple" } >db.fruit.find( {$and:[{"name" : "apple"},{"_id" : ObjectId("5e980a8b05d499f414a4e83d")}] } ) #多添加并存(都满足)and,另一种写法 { "_id" : ObjectId("5e980a8b05d499f414a4e83d"), "name" : "apple" } db.fruit.find( {$or:[{"name" : "apple"},{"_id" : ObjectId("5e980a8205d499f414a4e83c")}] } ) #or多条件只满足一个条件即可 { "_id" : ObjectId("5e980a7e05d499f414a4e839"), "name" : "apple" } { "_id" : ObjectId("5e980a8205d499f414a4e83a"), "name" : "apple" } { "_id" : ObjectId("5e980a8205d499f414a4e83c"), "name" : "orange" } { "_id" : ObjectId("5e980a8b05d499f414a4e83d"), "name" : "apple" } > db.fruit.find({"name" : /^o/ } ) 这则匹配 { "_id" : ObjectId("5e980a8205d499f414a4e83c"), "name" : "orange" }
查询条件对照表
SOL | mol |
a = 1 | {a: 1} |
a <> 1 | {a: {$ne: 1}} |
a > 1 | {a: {$gt: 1}} |
a >= 1 | {a: {$gte: 1}} |
a < 1 | {a: {$lt: 1}} |
a <= 1 | {a: {$lte: 1}} |
a = 1 AND b = 1 | {a: 1, b: 1}或{$and: [{a: 1}, {b: 1}]} |
a = 1 OR b = 1 | {$or: [{a: 1}, {b: 1}]} |
a IS NULL | {a: {$exists: false}} |
a IN (1, 2, 3) | {a: {$in: [1, 2, 3]}} |
查询逻辑运算符
● $lt: 存在并小于
● $lte: 存在并小于等于
● $gt: 存在并大于
● $gte: 存在并大于等于
● $ne: 不存在或存在但不等于
● $in: 存在并在指定数组中
● $nin: 不存在或不在指定数组中
● $or: 匹配两个或多个条件中的一个
● $and: 匹配全部条件
使用 find 搜索子文档
> db.fruit.drop() #删除操作 true > db.fruit.insertOne({ ... name: "apple", ... from: { ... country: "China", ... province: "Guangdon" ... } ... }) 重新插入 返回的信息 { "acknowledged" : true, "insertedId" : ObjectId("5e99090d05d499f414a4e83e") }
考虑以下查询的意义:
>db.fruit.find( { "from.country" : "China" } ) 语句表示查询一个子文档from.country 返回 { "_id" : ObjectId("5e99090d05d499f414a4e83e"), "name" : "apple", "from" : { "country" : "China", "province" : "Guangdon" } } > db.fruit.find( { "from" : {country: "China"} } )语句表示我要找from而且值是{country: "China"} 无返回
使用find搜索数据
> db.fruit.insert([ ... { "name" : "Apple", color: ["red", "green" ] }, ... { "name" : "Mango", color: ["yellow", "green"] } ... ]) 插入 返回 BulkWriteResult({ "writeErrors" : [ ], "writeConcernErrors" : [ ], "nInserted" : 2, "nUpserted" : 0, "nMatched" : 0, "nModified" : 0, "nRemoved" : 0, "upserted" : [ ] }) > db.fruit.find({color: "red"}) # color值包含red { "_id" : ObjectId("5e990b9305d499f414a4e83f"), "name" : "Apple", "color" : [ "red", "green" ] } { "_id" : ObjectId("5e990efa05d499f414a4e841"), "name" : "Apple", "color" : [ "red", "green" ] } > db.fruit.find({$or: [{color: "red"}, {color: "yellow"}]} ) 或的关系也是包含 { "_id" : ObjectId("5e990b9305d499f414a4e83f"), "name" : "Apple", "color" : [ "red", "green" ] } { "_id" : ObjectId("5e990b9305d499f414a4e840"), "name" : "Mango", "color" : [ "yellow", "green" ] } { "_id" : ObjectId("5e990efa05d499f414a4e841"), "name" : "Apple", "color" : [ "red", "green" ] } { "_id" : ObjectId("5e990efa05d499f414a4e842"), "name" : "Mango", "color" : [ "yellow", "green" ] }
使用 find 搜索数组中的对象
> db.movies.insertOne( { "title" : "Raiders of the Lost Ark", "filming_locations" : [ { "city" : "Los Angeles", "state" : "CA", "country" : "USA" }, { "city" : "Rome", "state" : "Lazio", "country" : "Italy" },
{ "city" : "Florence", "state" : "SC", "country" : "USA" } ] }) 语句 返回 { "acknowledged" : true, "insertedId" : ObjectId("5e9910fa05d499f414a4e843") }
// 查找城市是 Rome 的记录
db.movies.find({"filming_locations.city": "Rome"}) { "_id" : ObjectId("5e9910fa05d499f414a4e843"), "title" : "Raiders of the Lost Ark", "filming_locations" : [ { "city" : "Los Angeles", "state" : "CA", "country" : "USA" }, { "city" : "Rome", "state" : "Lazio", "country" : "Italy" }, { "city" : "Florence", "state" : "SC", "country" : "USA" } ] }
使用 find 搜索数组中的对象在数组中搜索子对象的多个字段时,如果使用 $elemMatch,它表示必须是同一个 子对象满足多个条件。考虑以下两个查询:
> db.getCollection('movies').find({ "filming_locations.city": "Rome", "filming_locations.country": "USA" }) 去重查询语句 返回 { "_id" : ObjectId("5e9910fa05d499f414a4e843"), "title" : "Raiders of the Lost Ark", "filming_locations" : [ { "city" : "Los Angeles", "state" : "CA", "country" : "USA" }, { "city" : "Rome", "state" : "Lazio", "country" : "Italy" }, { "city" : "Florence", "state" : "SC", "country" : "USA" } ] }
控制 find 返回的字段 ● find 可以指定只返回指定的字段; ● _id字段必须明确指明不返回,否则默认返回; ● 在 MongoDB 中我们称这为投影(projection);
> db.movies.find({},{"_id":0, title:1})#0表示不显示1表示显示 返回 { "title" : "Raiders of the Lost Ark" }
db.movies.find().pretty()与db.movies.find()的区别
> db.movies.find().pretty() 查询返回 { "_id" : ObjectId("5e9910fa05d499f414a4e843"), "title" : "Raiders of the Lost Ark", "filming_locations" : [ { "city" : "Los Angeles", "state" : "CA", "country" : "USA" }, { "city" : "Rome", "state" : "Lazio", "country" : "Italy" }, { "city" : "Florence", "state" : "SC", "country" : "USA" } ] } > db.movies.find() 查询返回 { "_id" : ObjectId("5e9910fa05d499f414a4e843"), "title" : "Raiders of the Lost Ark", "filming_locations" : [ { "city" : "Los Angeles", "state" : "CA", "country" : "USA" }, { "city" : "Rome", "state" : "Lazio", "country" : "Italy" }, { "city" : "Florence", "state" : "SC", "country" : "USA" } ] }
使用 remove 删除文档
remove 命令需要配合查询条件使用;
匹配查询条件的的文档会被删除;
指定一个空文档条件会删除所有文档;
db.testcol.remove( { a : 1 } ) // 删除a 等于1的记录 db.testcol.remove( { a : { $lt : 5 } } ) // 删除a 小于5的记录 db.testcol.remove( { } ) // 删除所有记录 db.testcol.remove() //报错
使用 update 更新文档
Update 操作执行格式:db.<集合>.update(<查询条件>, <更新字段>)
> db.fruit.insertMany([ {name: "apple"}, {name: "pear"}, {name: "orange"} ]) 语句 返回 { "acknowledged" : true, "insertedIds" : [ ObjectId("5e9917fe05d499f414a4e847"), ObjectId("5e9917fe05d499f414a4e848"), ObjectId("5e9917fe05d499f414a4e849") ] } > > db.fruit.find() 查看 { "_id" : ObjectId("5e9917fe05d499f414a4e847"), "name" : "apple" } { "_id" : ObjectId("5e9917fe05d499f414a4e848"), "name" : "pear" } { "_id" : ObjectId("5e9917fe05d499f414a4e849"), "name" : "orange" } > db.fruit.updateOne({name: "apple"}, {$set: {from: "China"}})更新添加查询 name 为apple 的记录;将找到添加的 from设置为 China { "acknowledged" : true, "matchedCount" : 1, "modifiedCount" : 1 } > db.fruit.find() 查看 { "_id" : ObjectId("5e9917fe05d499f414a4e847"), "name" : "apple", "from" : "China" } { "_id" : ObjectId("5e9917fe05d499f414a4e848"), "name" : "pear" } { "_id" : ObjectId("5e9917fe05d499f414a4e849"), "name" : "orange" }
使用 update 更新文档
● 使用 updateOne 表示无论条件匹配多少条记录,始终只更新第一条;
● 使用 updateMany 表示条件匹配多少条就更新多少条;
● updateOne/updateMany 方法要求更新条件部分必须具有以下之一,否则将报错:
• $set/$unset
• $push/$pushAll/$pop
• $pull/$pullAll
• $addToSet
● // 报错 db.fruit.updateOne({name: "apple"}, {from: "China"})
使用 update 更新数组
● $push: 增加一个对象到数组底部
● $pushAll: 增加多个对象到数组底部
● $pop: 从数组底部删除一个对象
● $pull: 如果匹配指定的值,从数组中删除相应的对象
● $pullAll: 如果匹配任意的值,从数据中删除相应的对象
● $addToSet: 如果不存在则增加一个值到数组
使用 drop 删除集合
● 使用 db.<集合>.drop() 来删除一个集合
● 集合中的全部文档都会被删除
● 集合相关的索引也会被删除 db.colToBeDropped.drop()
使用 dropDatabase 删除数据库
● 使用 db.dropDatabase() 来删除数据库
● 数据库相应文件也会被删除,磁盘空间将被释放
use tempDB
db.dropDatabase()
show collections // No collections
show dbs // The db is gone