MongoDB 入门系列（七）

find查找

简单查询

1. 新建mongodb-15.js，输入以下代码

var workmate1={
  name:'JSPang',
  age:33,
  sex:1,
  job:'前端',
  skill:{
      skillOne:'HTML+CSS',
      skillTwo:'JavaScript',
      skillThree:'PHP'
  },
  regeditTime:new Date(),
  interest:[]
}
var workmate2={
  name:'ShengLei',
  age:31,
  sex:1,
  job:'JAVA后端',
  skill:{
      skillOne:'HTML+CSS',
      skillTwo:'J2EE',
      skillThree:'PPT'
  },
  regeditTime:new Date(),
  interest:[]
}
var workmate3={
  name:'MinJie',
  age:18,
  sex:0,
  job:'UI',
  skill:{
      skillOne:'PhotoShop',
      skillTwo:'UI',
      skillThree:'PPT'
  },
  regeditTime:new Date(),
  interest:[]
}
var workmate4={
  name:'XiaoWang',
  age:25,
  sex:1,
  job:'UI',
  skill:{
      skillOne:'PhotoShop',
      skillTwo:'UI',
      skillThree:'PPT'
  },
  regeditTime:new Date(),
  interest:[]
}
var workmate5={
  name:'LiangPeng',
  age:28,
  sex:1,
  job:'前端',
  skill:{
      skillOne:'HTML+CSS',
      skillTwo:'JavaScript',
  },
  regeditTime:new Date(),
  interest:[]
}
var workmate6={
  name:'HouFei',
  age:25,
  sex:0,
  job:'前端',
  skill:{
      skillOne:'HTML+CSS',
      skillTwo:'JavaScript',
  },
  regeditTime:new Date(),
  interest:[]
}
var workmate7={
  name:'LiuYan',
  age:35,
  sex:0,
  job:'美工',
  skill:{
      skillOne:'PhotoShop',
      skillTwo:'CAD',
  },
  regeditTime:new Date(),
  interest:[]
}
var workmate8={
  name:'DingLu',
  age:20,
  sex:0,
  job:'美工',
  skill:{
      skillOne:'PhotoShop',
      skillTwo:'CAD',
  },
  regeditTime:new Date(),
  interest:[]
}
var workmate9={
  name:'JiaPeng',
  age:29,
  sex:1,
  job:'前端',
  skill:{
      skillOne:'HTML+CSS',
      skillTwo:'JavaScript',
      skillThree:'PHP'
  },
  regeditTime:new Date(),
  interest:[]
}
var workmate10={
  name:'LiJia',
  age:26,
  sex:0,
  job:'前端',
  skill:{
      skillOne:'HTML+CSS',
      skillTwo:'JavaScript',
      skillThree:'PHP'
  },
  regeditTime:new Date(),
  interest:[]
}
var db=connect('company');
var workmateArray=[workmate1,workmate2,workmate3,workmate4,workmate5,workmate6,workmate7,workmate8,workmate9,workmate10];
db.workmate.insert(workmateArray);
print('[SUCCESS]：The data was inserted successfully');

2. 使用find查找
   分别使用以下两个查询条件查找

db.workmate.find(
    {"skill.skillOne":"HTML+CSS"},
    {name:true,"skill.skillOne":true,_id:false}
)

// 得到下面内容
{ "name" : "JSPang", "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "ShengLei", "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "JSPang", "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "ShengLei", "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "LiangPeng", "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "HouFei", "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "JiaPeng", "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "LiJia", "skill" : { "skillOne" : "HTML+CSS" } }

db.workmate.find(     
    {"skill.skillOne":"HTML+CSS"},    
    {"skill.skillOne":true,_id:false} 
)

// 得到下面内容
{ "skill" : { "skillOne" : "HTML+CSS" } }
{ "skill" : { "skillOne" : "HTML+CSS" } }
{ "skill" : { "skillOne" : "HTML+CSS" } }
{ "skill" : { "skillOne" : "HTML+CSS" } }
{ "skill" : { "skillOne" : "HTML+CSS" } }
{ "skill" : { "skillOne" : "HTML+CSS" } }
{ "skill" : { "skillOne" : "HTML+CSS" } }
{ "skill" : { "skillOne" : "HTML+CSS" } }

可以得出find的第一个参数是查询条件，第二个参数是查找的包含字段所在层级，true为包含，默认false

其他参数：
不等修饰符

• 小于($lt):英文全称less-than
• 小于等于($lte)：英文全称less-than-equal
• 大于($gt):英文全称greater-than
• 大于等于($gte):英文全称greater-than-equal
• 不等于($ne):英文全称not-equal
  比如要查找年龄小于30大于25岁的人员，可以这样

> db.workmate.find(
     {age:{$lte:30,$gte:25}},
     {name:true,age:true,"skill.skillOne":true,_id:false}
 )
{ "name" : "ShengLei", "age" : 30, "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "XiaoWang", "age" : 25, "skill" : { "skillOne" : "PhotoShop" } }
{ "name" : "LiangPeng", "age" : 28, "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "HouFei", "age" : 25, "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "JiaPeng", "age" : 29, "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "LiJia", "age" : 26, "skill" : { "skillOne" : "HTML+CSS" } }

日期查找

> var startDate= new Date('01/01/2018');
> db.workmate.find(
     {regeditTime:{$gt:startDate}},
     {name:true,age:true,"skill.skillOne":true,_id:false}
 )
{ "name" : "JSPang", "age" : 33, "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "ShengLei", "age" : 30, "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "MinJie", "age" : 21, "skill" : { "skillOne" : "PhotoShop" } }
{ "name" : "JSPang", "age" : 33, "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "ShengLei", "age" : 31, "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "MinJie", "age" : 18, "skill" : { "skillOne" : "PhotoShop" } }
{ "name" : "XiaoWang", "age" : 25, "skill" : { "skillOne" : "PhotoShop" } }
{ "name" : "LiangPeng", "age" : 28, "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "HouFei", "age" : 25, "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "LiuYan", "age" : 35, "skill" : { "skillOne" : "PhotoShop" } }
{ "name" : "DingLu", "age" : 20, "skill" : { "skillOne" : "PhotoShop" } }
{ "name" : "JiaPeng", "age" : 29, "skill" : { "skillOne" : "HTML+CSS" } }
{ "name" : "LiJia", "age" : 26, "skill" : { "skillOne" : "HTML+CSS" } }

多条件查询

$in修饰符
in修饰符可以轻松解决一键多值的查询情况

db.workmate.find({age:{$in:[25,33]}},
    {name:1,"skill.skillOne":1,age:1,_id:0}
)

$or修饰符
它用来查询多个键值的情况

db.workmate.find({$or:[
    {age:{$gte:30}},
    {"skill.skillThree":'PHP'}
]},
    {name:1,"skill.skillThree":1,age:1,_id:0}
)

$and修饰符
它用来查找几个key值都满足的情况

db.workmate.find({$and:[
    {age:{$gte:30}},
    {"skill.skillThree":'PHP'}
]},
    {name:1,"skill.skillThree":1,age:1,_id:0}
)

$not修饰符
它用来查询除条件之外的值

db.workmate.find({
    age:{
        $not:{
            $lte:30,
            $gte:20
        }
    }
},
{name:1,"skill.skillOne":1,age:1,_id:0}
)

上面的几个修饰符建议多跑几种情况，看看是否符合预期，加深记忆。