MongoDB 查询文档

    pretty() 方法

    结果显示在一个格式化的方式，可以使用 pretty() 方法.

    语法:

    例子

    1. > db.mycol.find().pretty()
    2. {
    3.     "_id" : ObjectId("5799c3eb235910620b89c674"),
    4.     "title" : "MongoDB Overview",
    5.     "description" : "MongoDB is no sql database",
    6.     "by" : "tutorials itcast",
    7.     "url" : "http://www.itcast.cn",
    8.     "tags" : [
    9.         "mongodb",
    10.         "database",
    11.         "NoSQL"
    12.     ],
    13.     "likes" : 100
    14. }
    15. {
    16.     "_id" : ObjectId("5799c3f3235910620b89c675"),
    17.     "title" : "MySQL Overview",
    18.     "description" : "MySQL is sql database",
    19.     "by" : "tutorials itcast",
    20.     "url" : "http://www.itcast.cn",
    21.     "tags" : [
    22.         "MySQL",
    23.         "database",
    24.         "SQL"
    25.     ],
    26.     "likes" : 40
    27. >

    MongoDB 与 RDBMS Where 语句比较

    AND 在MongoDB中用法

    语法:

    在 find() 方法，如果通过多个键分离','，那么 MongoDB 处理 AND 条件。AND 基本语法如下所示：

    1. >db.mycol.find({key1:value1, key2:value2}).pretty()

    例子

    下面给出的例子将显示所有的教程，标题是“MongoDB Overview“

    1. > db.mycol.find({"by":"tutorials itcast","title": "MongoDB Overview"}).pretty()
    2. {
    3.   "_id" : ObjectId("5799c3eb235910620b89c674"),
    4.   "title" : "MongoDB Overview",
    5.   "description" : "MongoDB is no sql database",
    6.   "by" : "tutorials itcast",
    7.   "url" : "http://www.itcast.cn",
    9.     "mongodb",
    10.     "database",
    11.     "NoSQL"
    12.   ],
    13.   "likes" : 100
    14. }
    15. >

    MongoDB中OR

    语法:

    OR条件的基础上要查询文件，需要使用$or关键字。OR 基本语法如下所示：

    例子

    下面给出的例子将显示所有的教程，标题是“MongoDB Overview'或'MySQL Overview'

    1. >db.mycol.find({
    2.   $or: [
    3.     {
    4.       "title": "MySQL Overview"
    5.     },
    6.     {
    7.       "title": "MongoDB Overview"
    8.     }
    9.   ]
    10. }).pretty()
    11. {
    12.   "_id" : ObjectId("57cefded600d5bb1e2acdb70"),
    13.   "title" : "MongoDB Overview",
    14.   "description" : "MongoDB is no sql database",
    15.   "by" : "tutorials itcast",
    16.   "url" : "http://www.itcast.cn",
    17.   "tags" : [
    18.     "mongodb",
    19.     "database",
    20.     "NoSQL"
    21.   ],
    22.   "likes" : 100
    23. {
    24.   "_id" : ObjectId("57cefdf7600d5bb1e2acdb71"),
    25.   "title" : "MySQL Overview",
    26.   "description" : "MySQL is sql database",
    27.   "by" : "tutorials itcast",
    29.   "tags" : [
    30.     "MySQL",
    31.     "database",
    32.     "SQL"
    33.   ],
    34.   "likes" : 40
    35. }
    36. >

    AND 和 OR 一起使用

    例子

    1. > db.mycol.find({
    2.   "likes": {
    3.     $gt: 50
    4.   },
    5.   $or: [
    6.     {
    7.       "by": "tutorials itcast"
    8.     },
    9.     {
    10.       "title": "MongoDB Overview"
    11.     }
    12.   ]
    13. }).pretty()
    14. {
    15.   "_id" : ObjectId("57cefded600d5bb1e2acdb70"),
    16.   "title" : "MongoDB Overview",
    17.   "description" : "MongoDB is no sql database",
    18.   "by" : "tutorials itcast",
    19.   "url" : "http://www.itcast.cn",
    20.   "tags" : [
    21.     "mongodb",
    22.     "database",
    23.     "NoSQL"
    24.   ],
    25.   "likes" : 100
    26. >