Mongodb入門3
阿新 • • 發佈:2021-07-29
company資料庫下面heros集合裡的資料:
{ "_id" : ObjectId("6100c897d0c9f4158c2b0c9b"), "name" : "賈克斯", "age" : 55, "skill" : [ "跳斬", "蓄力一擊", "反擊風暴", "宗師之威" ] } { "_id" : ObjectId("6100c897d0c9f4158c2b0c9c"), "name" : "易", "age" : 22, "skill" : [ "阿 爾法突襲", "冥想", "無極劍道", "高原血統" ] } { "_id" : ObjectId("6100c897d0c9f4158c2b0c9d"), "name" : "德萊厄斯", "age" : 33, "skill" : [ "大殺四方", "致殘打擊", "無情鐵手", "諾克薩斯斷頭臺" ] } { "_id" : ObjectId("6100c897d0c9f4158c2b0c9e"), "name" : "趙信", "age" : 40, "skill" : [ "三重爪擊", "狂戰怒吼", "無畏衝鋒", "新月橫掃" ] } { "_id" : ObjectId("6100c897d0c9f4158c2b0c9f"), "name" : "嘉文四世", "age" : 30, "skill" : [ "巨龍撞擊", "黃金聖盾", "德瑪西亞軍旗", "天崩地裂" ] } { "_id" : ObjectId("6100c897d0c9f4158c2b0ca0"), "name" : "慎", "age" : 20, "skill" : [ "奧 義!暮臨", "奧義!魂佑", "奧義!影縛", "祕奧義!慈悲度魂落" ] } >
今天的內容比較簡單,主要是查詢的兩個限制條件 skip 和 limit
程式碼如下:
db.heros.find({}, { name: true, age: true, _id: false }).limit(2).skip(1*2).sort({ age: 1 });
查詢結果:
{ "name" : "嘉文四世", "age" : 30 } { "name" : "德萊厄斯", "age" : 33 }
$where 修飾符:
$where操作符功能強大且靈活,它可以將JavaScript表示式的字串或 JavaScript函式作為查詢語句的一部分。在JavaScri pt表示式和函式中,可以 使用this或obj來引用當前操作的文件
具體用法如下:
> db.heros.find( {$where:"this.age >30"}, { name: true, age: true, _id: false }
) { "name" : "賈克斯", "age" : 55 } { "name" : "德萊厄斯", "age" : 33 } { "name" : "趙信", "age" : 40 } >