MongoDB簡介
MongoDB 是一個基於分布式文件存儲的數據庫。由 C++ 語言編寫。旨在為 WEB 應用提供可擴展的高性能數據存儲解決方案。
MongoDB 是一個介於關系數據庫和非關系數據庫之間的產品,是非關系數據庫當中功能最豐富,最像關系數據庫的。
下面給大家介紹MongoDB查詢文檔操作的實例
先把student刪除,再重新插入數據
> db.student.drop() true > db.student.insert([{ "_id" : 1, "name" : "zhangsan", "age": 27, "sex": 1 }, { "_id" : 2, "name" : "lisi", "age": 27 } ,{ "_id" : 3, "name" : "wangwu", "age": 30 }, { "_id" : 4, "name" : "zhaoliu", "age": 28 }, { "_id" : 5, "name" : "qianliu", "age": 33 }, { "_id" : 6, "name" : "sunba", "age": 32 }]) BulkWriteResult({ "writeErrors" : [ ], "writeConcernErrors" : [ ], "nInserted" : 6, "nUpserted" : 0, "nMatched" : 0, "nModified" : 0, "nRemoved" : 0, "upserted" : [ ] }) > db.student.find() { "_id" : 1, "name" : "zhangsan", "age" : 27 } { "_id" : 2, "name" : "lisi", "age" : 27 } { "_id" : 3, "name" : "wangwu", "age" : 30 } { "_id" : 4, "name" : "zhaoliu", "age" : 28 } { "_id" : 5, "name" : "qianliu", "age" : 33 } { "_id" : 6, "name" : "sunba", "age" : 32 }
1、查詢指定鍵
db.集合名稱.find({查詢條件},{指定鍵})
指定鍵:1表示顯示,0表示不顯示,_id默認顯示
> db.student.find({},{name:1}) { "_id" : 1, "name" : "zhangsan" } { "_id" : 2, "name" : "lisi" } { "_id" : 3, "name" : "wangwu" } { "_id" : 4, "name" : "zhaoliu" } { "_id" : 5, "name" : "qianliu" } { "_id" : 6, "name" : "sunba" } > db.student.find({},{_id:0, age:0}) { "name" : "zhangsan", "sex" : 1 } { "name" : "lisi" } { "name" : "wangwu" } { "name" : "zhaoliu" } { "name" : "qianliu" } { "name" : "sunba" } > db.student.find({},{_id:0, name:1}) { "name" : "zhangsan" } { "name" : "lisi" } { "name" : "wangwu" } { "name" : "zhaoliu" } { "name" : "qianliu" } { "name" : "sunba" }
2、各種查詢方式
$lt:< $lte:<= $gt:> $gte:>= $ne:!= > db.student.find({age:{$lt:30}}) { "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 } { "_id" : 2, "name" : "lisi", "age" : 27 } { "_id" : 4, "name" : "zhaoliu", "age" : 28 } > db.student.find({age:{$ne:27}}) { "_id" : 3, "name" : "wangwu", "age" : 30 } { "_id" : 4, "name" : "zhaoliu", "age" : 28 } { "_id" : 5, "name" : "qianliu", "age" : 33 } { "_id" : 6, "name" : "sunba", "age" : 32 }
$in:包含
$nin:不包含
> db.student.find({age:{$in:[27,28]}}) { "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 } { "_id" : 2, "name" : "lisi", "age" : 27 } { "_id" : 4, "name" : "zhaoliu", "age" : 28 } > db.student.find({age:{$nin:[27,28]}}) { "_id" : 3, "name" : "wangwu", "age" : 30 } { "_id" : 5, "name" : "qianliu", "age" : 33 } { "_id" : 6, "name" : "sunba", "age" : 32 }
$or:或者
> db.student.find({$or:[{age:{$lt:29}}, {name:"sunba"}]}) { "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 } { "_id" : 2, "name" : "lisi", "age" : 27 } { "_id" : 4, "name" : "zhaoliu", "age" : 28 } { "_id" : 6, "name" : "sunba", "age" : 32 }
null:空值
> db.student.find({sex: null}) { "_id" : 2, "name" : "lisi", "age" : 27 } { "_id" : 3, "name" : "wangwu", "age" : 30 } { "_id" : 4, "name" : "zhaoliu", "age" : 28 } { "_id" : 5, "name" : "qianliu", "age" : 33 } { "_id" : 6, "name" : "sunba", "age" : 32 }
$type:鍵是某種類型的
double:1
string:2
...
> db.student.insert({_id:7, name:7, age:70}) WriteResult({ "nInserted" : 1 }) > db.student.find({name: {$type: 2}}) { "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 } { "_id" : 2, "name" : "lisi", "age" : 27 } { "_id" : 3, "name" : "wangwu", "age" : 30 } { "_id" : 4, "name" : "zhaoliu", "age" : 28 } { "_id" : 5, "name" : "qianliu", "age" : 33 } { "_id" : 6, "name" : "sunba", "age" : 32 } > db.student.find({name: {$type: 1}}) { "_id" : 7, "name" : 7, "age" : 70 }
正則表達式
> db.student.find({name: /si\b/}) { "_id" : 2, "name" : "lisi", "age" : 27 }
db.集合名稱.findOne({查詢條件},{指定鍵})
查詢出符合條件的第一條數據
> db.student.findOne() { "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 }
db.集合名稱.find({查詢條件},{指定鍵}).limit(數字)
查詢前幾條數據
> db.student.find().limit(3) { "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 } { "_id" : 2, "name" : "lisi", "age" : 27 } { "_id" : 3, "name" : "wangwu", "age" : 30 }
db.集合名稱.find({查詢條件},{指定鍵}).skip(數字)
跳過前幾條數據
> db.student.find().skip(2) { "_id" : 3, "name" : "wangwu", "age" : 30 } { "_id" : 4, "name" : "zhaoliu", "age" : 28 } { "_id" : 5, "name" : "qianliu", "age" : 33 } { "_id" : 6, "name" : "sunba", "age" : 32 } { "_id" : 7, "name" : 7, "age" : 70 }
可以使用limit()和skip()實現分頁
> db.student.find().skip(0).limit(3) { "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 } { "_id" : 2, "name" : "lisi", "age" : 27 } { "_id" : 3, "name" : "wangwu", "age" : 30 } > db.student.find().skip(3).limit(3) { "_id" : 4, "name" : "zhaoliu", "age" : 28 } { "_id" : 5, "name" : "qianliu", "age" : 33 } { "_id" : 6, "name" : "sunba", "age" : 32 } > db.student.find().skip(6).limit(3) { "_id" : 7, "name" : 7, "age" : 70 }
db.集合名稱.find().sort({鍵:數字})
數字為1表示升序,數字為2表示降序
> db.student.find().sort({age:1}) { "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 } { "_id" : 2, "name" : "lisi", "age" : 27 } { "_id" : 4, "name" : "zhaoliu", "age" : 28 } { "_id" : 3, "name" : "wangwu", "age" : 30 } { "_id" : 6, "name" : "sunba", "age" : 32 } { "_id" : 5, "name" : "qianliu", "age" : 33 } { "_id" : 7, "name" : 7, "age" : 70 } > db.student.find().sort({age:1, _id:-1}) { "_id" : 2, "name" : "lisi", "age" : 27 } { "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 } { "_id" : 4, "name" : "zhaoliu", "age" : 28 } { "_id" : 3, "name" : "wangwu", "age" : 30 } { "_id" : 6, "name" : "sunba", "age" : 32 } { "_id" : 5, "name" : "qianliu", "age" : 33 } { "_id" : 7, "name" : 7, "age" : 70 }
以上內容是小編給大家介紹的MongoDB快速入門筆記(四)之MongoDB查詢文檔操作實例代碼,希望對大家有所幫助!