在前面的文章里面主要介绍了MongoDB的文档，集合，数据库等操作和对文档的增、删、改相关知识，接下来会总结一点有关查询的相关知识。
在MySQL中,我们知道数据查询是优化的主要内容，读写分离等技术都是可以用来处理数据库查询优化的，足以见数据库查询是每个系统中很重要的一部分，之前介绍了find的简单使用，下面会介绍一些相对比较复杂一点的查询。
一、数据查询
MySQL数据库中主要是用select 结合where子句实现数据的查询，功能特别强大，例如多表联合查询、支持正则表达式等。不在这里做过多的相关介绍。这里主要介绍MongoDB的相关查询，MongoDB中主要用find()实现数据的查询，同时也可以使用一些条件限制。
1.1显示单条数据
在上篇文章中提到了find()的使用，但是每次查询数据，都是查询所有的，显示其中的一部分，可以用it迭代。有时候我们想要查询其中的一条数据，具体操作要根据具体需求实现。
MongoDB 查询数据的语法
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1
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db.collection.
find
(query, projection)
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query ：可选，使用查询操作符指定查询条件
projection ：可选，使用投影操作符指定返回的键。查询时返回文档中所有键值， 只需省略该参数即可（默认省略）。可以使用 pretty() 方法以易读的方式来读取数据，，语法格式如下
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>db.col.
find
().pretty()
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pretty() 方法以格式化的方式来显示所有文档。
例如：
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db.winner.
find
().pretty()
{
"_id"
: ObjectId(
"592e7d1caaa464fa8a557e95"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d1eaaa464fa8a557e96"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d1faaa464fa8a557e97"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d1faaa464fa8a557e98"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d21aaa464fa8a557e99"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d22aaa464fa8a557e9a"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec4"
),
"winne"
: 41 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec5"
),
"winne"
: 42 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec6"
),
"winne"
: 43 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec7"
),
"winne"
: 44 }
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1、查询某个集合中的所有数据
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db.winner.
find
()
{
"_id"
: ObjectId(
"592e7d1caaa464fa8a557e95"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d1eaaa464fa8a557e96"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d1faaa464fa8a557e97"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d1faaa464fa8a557e98"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d21aaa464fa8a557e99"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d22aaa464fa8a557e9a"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec4"
),
"winne"
: 41 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec5"
),
"winne"
: 42 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec6"
),
"winne"
: 43 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec7"
),
"winne"
: 44 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec8"
),
"winne"
: 45 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec9"
),
"winne"
: 46 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557eca"
),
"winne"
: 47 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ecb"
),
"winne"
: 48 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ecc"
),
"winne"
: 49 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ecd"
),
"winne"
: 50 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ece"
),
"winne"
: 51 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ecf"
),
"winne"
: 52 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ed0"
),
"winne"
: 53 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ed1"
),
"winne"
: 54 }
Type
"it"
for
more
|
默认显示20条数据，其他数据可以输入it迭代。
2、显示一条数据
find()是输出所有结果，里面可能有些文档内容相同，但是“_id”肯定是不一样的，这时我们可以使用findOne()方法查询，或者可以使用db.winner.find({winne:1955}).limit(1)。
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db.winner.
find
({winne:1955})
{
"_id"
: ObjectId(
"592e7d1caaa464fa8a557e95"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d1eaaa464fa8a557e96"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d1faaa464fa8a557e97"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d1faaa464fa8a557e98"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d21aaa464fa8a557e99"
),
"winne"
: 1955 }
{
"_id"
: ObjectId(
"592e7d22aaa464fa8a557e9a"
),
"winne"
: 1955 }
假如要查询winner集合中winne=1955的一条数据，而用
find
()查询出所有的数据，这时就可以使用findOne()
db.winner.findOne({winne:1955})
{
"_id"
: ObjectId(
"592e7d1caaa464fa8a557e95"
),
"winne"
: 1955 }
或者可以使用
db.winner.
find
({winne:1955}).limit(1)
{
"_id"
: ObjectId(
"592e7d1caaa464fa8a557e95"
),
"winne"
: 1955 }
两者的区别
findOne()有点类似MySQL里面的distinct,会返回查询的第一条结果，如果搜索不到想要的数据就会
返回NULL，
db.winner.findOne({winne:200888})
null
db.winner.
find
({winne:1955}).limit(1)方法就和MySQL里面的limit是一样的，主要是限制查询结果的条数。
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3、查询满足一定条件的数据
在MySQL中查询时，可以结合where以及字段等信息查询数据，而MongoDB中也是可以的，同样可以支持一些条件判断语句。
| 格式 | 范例 | RDBMS中的类似语句 | |
|---|---|---|---|
| 等于 | {<key>:<value>} |
db.col.find({"winne":"1995"}).pretty() |
where |
| 小于 | {<key>:{$lt:<value>}} |
db.col.find({" |
where |
| 小于或等于 | {<key>:{$lte:<value>}} |
db.col.find({" |
where |
| 大于 | {<key>:{$gt:<value>}} |
db.col.find({" |
where |
| 大于或等于 | {<key>:{$gte:<value>}} |
db.col.find({" |
where |
| 不等于 | {<key>:{$ne:<value>}} |
db.col.find({" |
where |
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$gt -------- greater than $gte --------- gt equal
$lt --------
less
than $lte --------- lt equal
$
ne
----------- not equal
1、查询winner集合中winne<50的相关数据
db.winner.
find
({winne:{$lt :50}})
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec4"
),
"winne"
: 41 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec5"
),
"winne"
: 42 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec6"
),
"winne"
: 43 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec7"
),
"winne"
: 44 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec8"
),
"winne"
: 45 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec9"
),
"winne"
: 46 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557eca"
),
"winne"
: 47 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ecb"
),
"winne"
: 48 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ecc"
),
"winne"
: 49 }
{
"_id"
: ObjectId(
"592e7e17aaa464fa8a557f28"
),
"winne"
: 41 }
{
"_id"
: ObjectId(
"592e7e17aaa464fa8a557f29"
),
"winne"
: 42 }
{
"_id"
: ObjectId(
"592e7e17aaa464fa8a557f2a"
),
"winne"
: 43 }
{
"_id"
: ObjectId(
"592e7e17aaa464fa8a557f2b"
),
"winne"
: 44 }
2、查询winner集合中40=<winne<50的相关数据
db.winner.
find
({winne:{$gte:40,$lt:45}})
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec4"
),
"winne"
: 41 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec5"
),
"winne"
: 42 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec6"
),
"winne"
: 43 }
{
"_id"
: ObjectId(
"592e7e14aaa464fa8a557ec7"
),
"winne"
: 44 }
{
"_id"
: ObjectId(
"592e7e17aaa464fa8a557f28"
),
"winne"
: 41 }
{
"_id"
: ObjectId(
"592e7e17aaa464fa8a557f29"
),
"winne"
: 42 }
{
"_id"
: ObjectId(
"592e7e17aaa464fa8a557f2a"
),
"winne"
: 43 }
{
"_id"
: ObjectId(
"592e7e17aaa464fa8a557f2b"
),
"winne"
: 44 }
{
"_id"
: ObjectId(
"592e7e18aaa464fa8a557f8c"
),
"winne"
: 41 }
{
"_id"
: ObjectId(
"592e7e18aaa464fa8a557f8d"
),
"winne"
: 42 }
{
"_id"
: ObjectId(
"592e7e18aaa464fa8a557f8e"
),
"winne"
: 43 }
{
"_id"
: ObjectId(
"592e7e18aaa464fa8a557f8f"
),
"winne"
: 44 }
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4、MongoDB AND 条件
MongoDB 的 find() 方法可以传入多个键(key)，每个键(key)以逗号隔开，语法格式如下：
>db.winner.find({key1:value1, key2:value2}).pretty()
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#插入测试数据
for
(i=0;i<20;i++)db.info2.insert({name:
"linux"
,
object:
"SA"
,
company:
"docker"
,
phone:i})
for
(i=0;i<20;i++)db.info2.insert({name:
"openstack"
,
object:
"DBA"
,
company:
"could"
,
phone:i})
#检查测试数据
> db.info2.
find
()
db.info2.
find
()
{
"_id"
: ObjectId(
"592f838dd276944818f7edb4"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 0 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb5"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 1 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb6"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb7"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb8"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 4 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb9"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 5 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edba"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 6 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbb"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 7 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbc"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 8 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbd"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 9 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbe"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 10 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbf"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 11 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc0"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 12 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc1"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 13 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc2"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 14 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc3"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 15 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc4"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 16 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc5"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 17 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc6"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 18 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc7"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 19 }
>db.info2.
find
().count()
#检查数据的条数
40
#筛选name=linux object=SA phone<5
db.info2.
find
({name:
"linux"
,object:
"SA"
,phone:{$lt:5}})
执行
db.info2.
find
({name:
"linux"
,object:
"SA"
,phone:{$lt:5}})
{
"_id"
: ObjectId(
"592f838dd276944818f7edb4"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 0 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb5"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 1 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb6"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb7"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb8"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 4 }
筛选name=linux object=SA 5<phone<=10
db.info2.
find
({name:
"linux"
,object:
"SA"
,phone:{
"$gt"
:5,
"$lte"
:10}})
db.info2.
find
({name:
"linux"
,object:
"SA"
,phone:{
"$gt"
:5,
"$lte"
:10}})
{
"_id"
: ObjectId(
"592f838dd276944818f7edba"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 6 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbb"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 7 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbc"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 8 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbd"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 9 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbe"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 10 }
筛选 5<phone<=10
db.info2.
find
({phone:{
"$gt"
:5,
"$lte"
:10}})
{
"_id"
: ObjectId(
"592f838dd276944818f7edba"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 6 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbb"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 7 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbc"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 8 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbd"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 9 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbe"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 10 }
{
"_id"
: ObjectId(
"592f838fd276944818f7edce"
),
"name"
:
"openstack"
,
"object"
:
"DBA"
,
"company"
:
"could"
,
"phone"
: 6 }
{
"_id"
: ObjectId(
"592f838fd276944818f7edcf"
),
"name"
:
"openstack"
,
"object"
:
"DBA"
,
"company"
:
"could"
,
"phone"
: 7 }
{
"_id"
: ObjectId(
"592f838fd276944818f7edd0"
),
"name"
:
"openstack"
,
"object"
:
"DBA"
,
"company"
:
"could"
,
"phone"
: 8 }
{
"_id"
: ObjectId(
"592f838fd276944818f7edd1"
),
"name"
:
"openstack"
,
"object"
:
"DBA"
,
"company"
:
"could"
,
"phone"
: 9 }
{
"_id"
: ObjectId(
"592f838fd276944818f7edd2"
),
"name"
:
"openstack"
,
"object"
:
"DBA"
,
"company"
:
"could"
,
"phone"
: 10 }
|
5 MongoDB OR 条件
MongoDB 除了有类似MySQL的AND条件语句外，还有OR 条件语句，OR 条件语句使用了关键字 $or,语法格式如下：
>db.collections.find(
{
$or: [
{key1: value1}, {key2:value2}
]
}
).pretty()
|
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43
|
#查name=linux 或者object=redis
db.info2.
find
(
{$or:[{name:
"linux"
},{object:
"redis"
}]
}
)
db.info2.
find
(db.info2.
find
(
... {$or:[{name:
"linux"
},{object:
"redis"
}]{$or:[{name:
"linux"
},{object:
"redis"
}]
...
... }}
... ))
{
"_id"
: ObjectId(
"592f838dd276944818f7edb4"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 0 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb5"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 1 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb6"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb7"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb8"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 4 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb9"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 5 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edba"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 6 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbb"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 7 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbc"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 8 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbd"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 9 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbe"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 10 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edbf"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 11 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc0"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 12 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc1"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 13 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc2"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 14 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc3"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 15 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc4"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 16 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc5"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 17 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc6"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 18 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edc7"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 19 }
Type
"it"
for
more
> itit
{
"_id"
: ObjectId(
"592f8964d276944818f7eddc"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 0 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddd"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 1 }
{
"_id"
: ObjectId(
"592f8964d276944818f7edde"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddf"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f8964d276944818f7ede0"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 4 }
{
"_id"
: ObjectId(
"592f8964d276944818f7ede1"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 5 }
{
"_id"
: ObjectId(
"592f8964d276944818f7ede2"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 6 }
{
"_id"
: ObjectId(
"592f8964d276944818f7ede3"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 7 }
{
"_id"
: ObjectId(
"592f8964d276944818f7ede4"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 8 }
{
"_id"
: ObjectId(
"592f8964d276944818f7ede5"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 9 }
|
6、AND和OR综合使用
查询phone<5,name=MongoDB或者name=linux
|
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2
3
4
5
6
7
8
9
10
11
12
|
db.info2.
find
({phone:{$lt:5},$or:[{name:
"MongoDB"
},{name:
"linux"
}]})
db.info2.
find
({phone:{$lt:5},$or:[{name:
"MongoDB"
},{name:
"linux"
}]})
{
"_id"
: ObjectId(
"592f838dd276944818f7edb4"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 0 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb5"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 1 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb6"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb7"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb8"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 4 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddc"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 0 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddd"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 1 }
{
"_id"
: ObjectId(
"592f8964d276944818f7edde"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddf"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f8964d276944818f7ede0"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 4 }
|
7、查询结果排序
在MySQL中是有order by条件，可以根据desc或者asc进行升序或者降序操作，而MongoDB中是可以利用sort()方法实现排序的，例如对6中的结果处理，根据phone排序。
基本语法
db.info2.find().sort({phone:1}) #这里phone表示根据该key排序，1表示升序，-1表示降序。
|
1
2
3
4
5
6
7
8
9
10
11
|
db.info2.
find
({phone:{$lt:5},$or:[{name:
"MongoDB"
},{name:
"linux"
}]}).
sort
({phone:1})
{
"_id"
: ObjectId(
"592f838dd276944818f7edb4"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 0 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddc"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 0 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb5"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 1 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddd"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 1 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb6"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f8964d276944818f7edde"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb7"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddf"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb8"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 4 }
{
"_id"
: ObjectId(
"592f8964d276944818f7ede0"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 4 }
|
8、MongoDB Skip() 方法
在前面介绍了limit()，sort()，count()等方法，接下来要介绍一个比较有趣的skip()方法，在使用limit()的时候可以显示你要求的几条，而skip()方法是跳过几条。
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
|
db.info2.
find
({phone:{$lt:5},$or:[{name:
"MongoDB"
},{name:
"linux"
}]}).
sort
({phone:1})
{
"_id"
: ObjectId(
"592f838dd276944818f7edb4"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 0 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddc"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 0 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb5"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 1 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddd"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 1 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb6"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f8964d276944818f7edde"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb7"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddf"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb8"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 4 }
{
"_id"
: ObjectId(
"592f8964d276944818f7ede0"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 4 }
使用skip()方法
db.info2.
find
({phone:{$lt:5},$or:[{name:
"MongoDB"
},{name:
"linux"
}]}).
sort
({phone:1}).skip(3)
{
"_id"
: ObjectId(
"592f8964d276944818f7eddd"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 1 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb6"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f8964d276944818f7edde"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 2 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb7"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f8964d276944818f7eddf"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 3 }
{
"_id"
: ObjectId(
"592f838dd276944818f7edb8"
),
"name"
:
"linux"
,
"object"
:
"SA"
,
"company"
:
"docker"
,
"phone"
: 4 }
{
"_id"
: ObjectId(
"592f8964d276944818f7ede0"
),
"name"
:
"MongoDB"
,
"object"
:
"redis"
,
"company"
:
"winner"
,
"phone"
: 4 }
skip 方法有点类似于MySQL里面的limit之间间隔情况。
|
这里介绍了有关查询的问题，在数据库中，查询是非常重要的一部分，所以介绍的篇幅也是比较多的，后期遇到其他问题也会继续总结输出。
本文转自 tianya1993 51CTO博客，原文链接：http://blog.51cto.com/dreamlinux/1931384，如需转载请自行联系原作者
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