• 技术文章 >数据库 >MongoDB

    mongodb怎么查询数据

    爱喝马黛茶的安东尼爱喝马黛茶的安东尼2019-11-19 13:49:41原创2672

    1、插入测试数据

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    use flower

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    db.goods.insert({'goods_name':'Hyacinth',price:10,num:800})

    db.goods.insert({goods_name:'Hyacinth',price:10,num:800})

    db.goods.insert({goods_name:'violet',price:20,num:1000})

    db.goods.insert({goods_name:'Plum blossom',price:20,num:1000})

    db.goods.insert({goods_name:'Datura',price:40,num:700})

    db.goods.insert({goods_name:'Rosemary',price:39,num:2000})

    db.goods.insert({goods_name:'Rosemary',price:39,num:2000,area:{province:'beijing','city':'beijing'}})

    db.goods.insert({goods_name:'Rosemary',price:39,num:2000,area:{province:'Shanghai','city':'Shanghai'}})

    db.goods.insert({goods_name:'Chinese rose',price:67,num:3700,area:{province:'Henan','city':'Luoyang'}})

    db.goods.insert({goods_name:'Chinese rose',price:32,num:900,area:{province:'Henan','city':'Luoyang'}})

    db.goods.insert({goods_name:'Chinese rose',price:32,num:900,area:{province:'Henan','city':'Luoyang'},color:

    ['write','red']})

    db.goods.insert({goods_name:'Chinese rose',price:32,num:900,area:{province:'Henan','city':'Luoyang'},color:

    ['red','green']})

    db.goods.insert({goods_name:'Chinese rose',price:32,num:900,area:{province:'Henan','city':'Luoyang'},color:

    ['write','red','grees']})

    添加数据的方式：普通数据的添加、多维数据的添加、数组数据的添加

    2、MongoDB命令行查询数据

    MongoDB命令行查询数据有以下几种方式：

    ·笼统方式查询

    ·条件限制查询

    ·范围查询

    ·多个查询条件

    ·多维字段的查询

    ·数组条件的限制查询

    ·字段的限制查询

    1）笼统方式查询：

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    db.goods.find()

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    db.goods.find()

    { "_id" : ObjectId("5cb5bba28a0ad00bec55f14b"), "goods_name" : "Hyacinth", "price" : 10, "num" : 800 }

    { "_id" : ObjectId("5cb5bba28a0ad00bec55f14c"), "goods_name" : "Hyacinth", "price" : 10, "num" : 800 }

    { "_id" : ObjectId("5cb5bba28a0ad00bec55f14d"), "goods_name" : "violet", "price" : 20, "num" : 1000 }

    ……

    采用这种方式查询，会查询所有数据。

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    db.goods.findOne()

    查询所有数据中的第一条，并且将数据格式化输出。

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    db.goods.findOne()

    {

    "_id" : ObjectId("5cb5bba28a0ad00bec55f14b"),

    "goods_name" : "Hyacinth",

    "price" : 10,

    "num" : 800

    }

    2）条件限制查询

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    db.goods.find({goods_name:'Hyacinth'})

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    { "_id" : ObjectId("5cb5bba28a0ad00bec55f14b"), "goods_name" : "Hyacinth", "price" : 10, "num" : 800 }

    { "_id" : ObjectId("5cb5bba28a0ad00bec55f14c"), "goods_name" : "Hyacinth", "price" : 10, "num" : 800 }

    相当于：SELECT *FROM goods WHERE goods_name='Hyacinth'

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    db.goods.findOne({goods_name:'Hyacinth'})

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    {

    "_id" : ObjectId("5cb5bba28a0ad00bec55f14b"),

    "goods_name" : "Hyacinth",

    "price" : 10,

    "num" : 800

    }

    该_id字段的内容值是MongoDB本身算法获得出来的，_id字段对应的值是“全球唯一”的，相当于MySQL表里的主键id，是唯一的。id可以自行设置，但是不推荐。

    优点：方便MongoDB的数据做升级、迁移

    3）范围查询

    查询goods表中价格大于10的数据：

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    db.goods.find({price:{'$gt':10}})

    查询goods表中价格大于等于10的数据：

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    db.goods.find({price:{'$gte':10}})

    查询goods表中价格小于10的数据：

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    db.goods.find({price:{'$lt':12}})

    查询goods表中价格小于等于10的数据：

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    db.goods.find({price:{'$lte':12}})

    4）多个查询条件

    例如：要求price大于10，库存大于800

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    db.goods.find({price:{'$gt':10},num:{'$gt':800}})

    要求price大于10，库存为900

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    db.goods.find({price:{'$gt':10},num:900})

    5）多维字段的查询

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    db.goods.find({'area.province':'Shanghai'})

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    db.goods.find({'area.city':'Shanghai'})

    6）数组条件的限制查询

    查询“color”中有“red”记录，满足一个元素即可：

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    db.goods.find({color:'red'})

    查询“color”中有“red”并且(AND)有“write”的记录：

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    db.goods.find({color:{'$all':['red','write']}})

    查询“price”是10或者(OR)“num”是800

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    db.goods.find({$or:[{'price':10},{'num':800}]})

    7）字段的限制查询

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    db.goods.find({price:32},{goods_name:1})

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    { "_id" : ObjectId("5cb5bba28a0ad00bec55f154"), "goods_name" : "Chinese rose" }

    { "_id" : ObjectId("5cb5bba28a0ad00bec55f155"), "goods_name" : "Chinese rose" }

    { "_id" : ObjectId("5cb5bba28a0ad00bec55f156"), "goods_name" : "Chinese rose" }

    { "_id" : ObjectId("5cb5bba48a0ad00bec55f157"), "goods_name" : "Chinese rose" }

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    db.goods.find({price:32},{goods_name:1,_id:0})

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    { "goods_name" : "Chinese rose" }

    { "goods_name" : "Chinese rose" }

    { "goods_name" : "Chinese rose" }

    { "goods_name" : "Chinese rose" }

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    db.goods.find({price:{'$gt':30}},{goods_name:1,_id:0})

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    { "goods_name" : "Datura" }

    { "goods_name" : "Rosemary" }

    { "goods_name" : "Rosemary" }

    { "goods_name" : "Rosemary" }

    { "goods_name" : "Chinese rose" }

    { "goods_name" : "Chinese rose" }

    { "goods_name" : "Chinese rose" }

    { "goods_name" : "Chinese rose" }

    { "goods_name" : "Chinese rose" }

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    db.goods.find({price:{'$gt':30}},{goods_name:1,price:1,_id:0})

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    { "goods_name" : "Datura", "price" : 40 }

    { "goods_name" : "Rosemary", "price" : 39 }

    { "goods_name" : "Rosemary", "price" : 39 }

    { "goods_name" : "Rosemary", "price" : 39 }

    { "goods_name" : "Chinese rose", "price" : 67 }

    { "goods_name" : "Chinese rose", "price" : 32 }

    { "goods_name" : "Chinese rose", "price" : 32 }

    { "goods_name" : "Chinese rose", "price" : 32 }

    { "goods_name" : "Chinese rose", "price" : 32 }

    说明：_id字段除外，其它字段可以随意设置0，1。可以设置全部字段都输出，也设置为全部字段都不输出。但是，字段中一个是1，另一个是0，这是不可以。

    python学习网，大量的免费MongoDB入门教程，欢迎在线学习！

    专题推荐：mongodb 查询数据
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