MongoDB查询语句简要分析

sudo service mongodb start

mongo

> use post #创建post数据库，并向其中插入文档
> db.post.insert([
{
   title: 'MongoDB Overview', 
   description: 'MongoDB is no sql database',
   by: 'shiyanlou',
   url: 'http://www.shiyanlou.com',
   tags: ['mongodb', 'database', 'NoSQL'],
   likes: 100
},
{
   title: 'NoSQL Database', 
   description: "NoSQL database doesn't have tables",
   by: 'shiyanlou',
   url: 'http://www.shiyanlou.com',
   tags: ['mongodb', 'database', 'NoSQL'],
   likes: 20, 
   comments: [    
      {
         user:'user1',
         message: 'My first comment',
         dateCreated: new Date(2013,11,10,2,35),
         like: 0 
      }
   ]
}
])

db.post.find()

pretty() 语句

db.post.find().pretty()

MongoDB中的 AND

当 find() 中传入多个键值对时，MongoDB就会将其作为 AND 查询处理。用法：db.mycol.find({ key1: value1, key2: value2 }).pretty()

db.post.find({"by":"shiyanlou","title": "MongoDB Overview"}).pretty()

> db.post.find(
   {
      $or: [
         {key1: value1}, {key2:value2}
      ]
   }
).pretty()

> db.post.find({
    "likes": {$gt:10},
    $or: [
        {"by": "shiyanlou"},
        {"title": "MongoDB Overview"}
    ]
}).pretty() #<span style="color: rgb(51, 51, 51); font-family: 'Microsoft Yahei'; font-size: 16px; line-height: 25.59375px;">{\$gt:10} 表示大于10，另外，\$lt 表示小于，\$lte 表示小于等于，\$gte 表示大于等于，\$ne 表示不等于。</span>