mongodb remove update find

uykh

更新

语法如下：

    使用update方法来更新集合中的数据。update有四个参数，前两个参数是必须的。

    db.person.update({"name”:”meteor”},{“$set":{"age":35}},true,true);

    第一个参数：查询器，定位需要更新的目标文档(定义匹配条件)。

    第二个参数：修改器文档，指定修改内容。

    第三个参数：true表示要使用upsert，即如果没有找到符合更新条件的文档，就会以这个条件和更新文档为基础创建一个新的文档。如果找到了匹配的文档，则正常更新。

    第四个参数：true表示符合条件的所有文档，都要执行更新。

修改器

$set：用来指定一个字段的值。如果这个字段不存在，则创建它。对于更新而言，对符合更新条件的文档，修改执行的字段，不需要全部覆盖。

> db.emp.find()

{ "_id" : 1, "ename" : "tom", "age" : 25, "department" : "Sales", "salary" : 6000 }

{ "_id" : 2, "ename" : "eric", "age" : 24, "department" : "HR", "salary" : 4500 }

{ "_id" : 3, "ename" : "robin", "age" : 30, "department" : "Sales", "salary" : 8000 }

{ "_id" : 4, "ename" : "jack", "age" : 28, "department" : "Development", "salary" : 8000 }

{ "_id" : 5, "ename" : "Mark", "age" : 22, "department" : "Development", "salary" : 6500 }

{ "_id" : 6, "ename" : "marry", "age" : 23, "department" : "Planning", "salary" : 5000 }

{ "_id" : 7, "ename" : "hellen", "age" : 32, "department" : "HR", "salary" : 6000 }

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 7000 }

> db.emp.find().forEach(

... function(item){

...  db.emp.update({"_id":item._id},{"$set": {"salary":item.salary+item.salary*.2}},false,true)

... })

> db.emp.find()

{ "_id" : 1, "ename" : "tom", "age" : 25, "department" : "Sales", "salary" : 7200 }

{ "_id" : 2, "ename" : "eric", "age" : 24, "department" : "HR", "salary" : 5400 }

{ "_id" : 3, "ename" : "robin", "age" : 30, "department" : "Sales", "salary" : 9600 }

{ "_id" : 4, "ename" : "jack", "age" : 28, "department" : "Development", "salary" : 9600 }

{ "_id" : 5, "ename" : "Mark", "age" : 22, "department" : "Development", "salary" : 7800 }

{ "_id" : 6, "ename" : "marry", "age" : 23, "department" : "Planning", "salary" : 6000 }

{ "_id" : 7, "ename" : "hellen", "age" : 32, "department" : "HR", "salary" : 7200 }

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400 }

>

$inc：用来增加已有键的值，或者该键不存在就创建一个

> db.emp.update({},{$inc:{"age":2}},false,true)

WriteResult({ "nMatched" : 8, "nUpserted" : 0, "nModified" : 8 })

> db.emp.find()

{ "_id" : 1, "ename" : "tom", "age" : 27, "department" : "Sales", "salary" : 7200 }

{ "_id" : 2, "ename" : "eric", "age" : 26, "department" : "HR", "salary" : 5400 }

{ "_id" : 3, "ename" : "robin", "age" : 32, "department" : "Sales", "salary" : 9600 }

{ "_id" : 4, "ename" : "jack", "age" : 30, "department" : "Development", "salary" : 9600 }

{ "_id" : 5, "ename" : "Mark", "age" : 24, "department" : "Development", "salary" : 7800 }

{ "_id" : 6, "ename" : "marry", "age" : 25, "department" : "Planning", "salary" : 6000 }

{ "_id" : 7, "ename" : "hellen", "age" : 34, "department" : "HR", "salary" : 7200 }

{ "_id" : 8, "ename" : "sarah", "age" : 26, "department" : "Development", "salary" : 8400 }

> db.emp.update({},{$inc:{"age":-2}},false,true)

WriteResult({ "nMatched" : 8, "nUpserted" : 0, "nModified" : 8 })

> db.emp.find()

{ "_id" : 1, "ename" : "tom", "age" : 25, "department" : "Sales", "salary" : 7200 }

{ "_id" : 2, "ename" : "eric", "age" : 24, "department" : "HR", "salary" : 5400 }

{ "_id" : 3, "ename" : "robin", "age" : 30, "department" : "Sales", "salary" : 9600 }

{ "_id" : 4, "ename" : "jack", "age" : 28, "department" : "Development", "salary" : 9600 }

{ "_id" : 5, "ename" : "Mark", "age" : 22, "department" : "Development", "salary" : 7800 }

{ "_id" : 6, "ename" : "marry", "age" : 23, "department" : "Planning", "salary" : 6000 }

{ "_id" : 7, "ename" : "hellen", "age" : 32, "department" : "HR", "salary" : 7200 }

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400 }

>

$push：向已有数组末尾加入一个元素

> db.emp.update({"ename":"sarah"},{"$set":{"language":["Chinese"]}},true,true)  //对符合name等于sarah的文档，添加一个language的数组

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.emp.find({"ename":"sarah"})

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400, "language" : [ "Chinese" ] }

> db.emp.update({"ename":"sarah"},{"$push":{"language":"English"}},true,true)  //给数组的末尾添加一个值

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.emp.find({"ename":"sarah"})

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400, "language" : [ "Chinese", "English" ] }

>  

$addToSet：避免向数组插入重复的值

> db.emp.update({"ename":"sarah"},{"$addToSet":{"language":"English"}},true,true)

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })

> db.emp.update({"ename":"sarah"},{"$addToSet":{"language":"Russian"}},true,true)

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.emp.find({"ename":"sarah"})

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400, "language" : [ "Chinese", "English", "Russian" ] }

> db.emp.update({"ename":"sarah"},{"$addToSet":{"language":"Russian"}},true,true)

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })

> db.emp.find({"ename":"sarah"})

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400, "language" : [ "Chinese", "English", "Russian" ] }

>

$each：与$push和$addToSet结合，一次给数组添加多个值

> db.emp.update({"ename":"sarah"},{"$addToSet":{"language":{"$each":["German","French"]}}},true,true)

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.emp.find({"ename":"sarah"})

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400, "language" : [ "Chinese", "English", "Russian", "German", "French" ] }

>

$pop：可以从数组的任何一端删除元素

> db.emp.update({"ename":"sarah"},{"$pop":{"language":1}},true,true)//从数组的末尾删除一个元素

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.emp.find({"ename":"sarah"})

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400, "language" : [ "Chinese", "English", "Russian", "German" ] }

> db.emp.update({"ename":"sarah"},{"$pop":{"language":-1}},true,true)//从数组的头部删除一个元素

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.emp.find({"ename":"sarah"})

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400, "language" : [ "English", "Russian", "German" ] }

>

$pull：删除数组对应的值

> db.emp.update({"ename":"sarah"},{"$pull":{"language":"Russian"}},true,true)

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.emp.find({"ename":"sarah"})

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400, "language" : [ "English", "German" ] }

> db.emp.update({"ename":"sarah"},{"$pull":{"language":"German"}},true,true)

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.emp.find({"ename":"sarah"})

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400, "language" : [ "English" ] }

$unset : 删除文档中指定的字段

> db.emp.update({"ename":"sarah"},{"$unset":{"language":1}},true,true)

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.emp.find({"ename":"sarah"})

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400 }

>

符合条件的文档只更新第一条记录，如果没有更新字段，则添加：

db.col.update( { "age" : { $gt : 25 } } , { $set : { "test2" : "OK"} } );

符合条件的文档只更新第一条记录，如果没有更新字段，则忽略：

db.col.update( { "age" : { $gt : 25 } } , { $inc : { "age" : 1} },false,false);

符合条件的文档全部更新，如果没有更新字段，则添加：

db.col.update( { "age" : { $gt : 25 } } , { $set : { "test2" : "OK"} },false,true );

符合条件的文档只添加第一条，如果没有更新字段，则添加：

db.col.update( { "age" : { $gt : 25 } } , { $set : { "test2” : "OK"} },true,false );

符合条件的文档全部添加加进去(覆盖原始字段的值):

db.col.update( { "age" : { $gt : 25 } } , { $set : { "test2” : "OK"} },true,true );

删除

    使用remove方法删除集合中的数据。它可以接受一个查询文档作为可选参数。给定这个参数以后，只有符合条件的文档才能被删除。（删除数据是永久性的，不能撤销，也不能恢复）。

    db.emp.remove({"name”:”sarah”})//删除person集合中name字段的值等于ryan的所有文档。

    db.emp.remove()//删除person集合中所有的文档。

    使用drop方法代替remove方法，可以大幅度提高删除数据的速度。但是这个方法不能指定任何限定条件。而且整个集合都会被删除，包括索引等信息，甚用！！

    db.emp.drop()

查询

    MongoDB中使用find方法来进行查询。查询就是返回一个集合中文档的子集，子集的范围从0个文档到整个集合。

find方法接受两个参数:

    第一个参数决定了要返回哪些文档，参数的内容是查询的条件。

    第二个参数来指定想要的键(字段)。第二个参数存在的情况：键的值为1代表要显示，为0代表不显示。“_id”默认显示，其他默认不显示。第二个参数不存在的情况：所有字段默认显示。

> db.emp.find({"ename":"sarah"},{"ename":1})

{ "_id" : 8, "ename" : "sarah" }

>

查询条件：

$lt、$lte、$gt、$gte 比较操作符(没有$eq这个操作符)，分别对应<、<=、>、>=。

> db.emp.find({"age":{"$lt":25}},{"ename":1})

{ "_id" : 2, "ename" : "eric" }

{ "_id" : 5, "ename" : "Mark" }

{ "_id" : 6, "ename" : "marry" }

{ "_id" : 8, "ename" : "sarah" }

> db.emp.find({"age":{"$gt":25}},{"ename":1})

{ "_id" : 3, "ename" : "robin" }

{ "_id" : 4, "ename" : "jack" }

{ "_id" : 7, "ename" : "hellen" }

> db.emp.find({"age":25},{"ename":1})

{ "_id" : 1, "ename" : "tom" }

>

$in、$nin，用来查询一个键的多个值。

> db.emp.find({"age":{"$in":[22,25,28]}},{"ename":1})

{ "_id" : 1, "ename" : "tom" }

{ "_id" : 4, "ename" : "jack" }

{ "_id" : 5, "ename" : "Mark" }

> db.emp.find({"age":{"$nin":[22,25,28]}},{"ename":1})

{ "_id" : 2, "ename" : "eric" }

{ "_id" : 3, "ename" : "robin" }

{ "_id" : 6, "ename" : "marry" }

{ "_id" : 7, "ename" : "hellen" }

{ "_id" : 8, "ename" : "sarah" }

>

$or，用来查询多个键的多个值(可以和$in等配合使用)

> db.emp.find({"$or":[{"age":25},{"salary":7800}]},{"ename":1,_id:0,age:1,salary:1})

{ "ename" : "tom", "age" : 25, "salary" : 7200 }

{ "ename" : "Mark", "age" : 22, "salary" : 7800 }

>

$exists，查询的键对应是值是null的，默认会返回null和键不存在的文档。可以通过$exists来判断该键是否存在。

> db.emp.find({"language":{"$exists":false}})

{ "_id" : 1, "ename" : "tom", "age" : 25, "department" : "Sales", "salary" : 7200 }

{ "_id" : 2, "ename" : "eric", "age" : 24, "department" : "HR", "salary" : 5400 }

{ "_id" : 3, "ename" : "robin", "age" : 30, "department" : "Sales", "salary" : 9600 }

{ "_id" : 4, "ename" : "jack", "age" : 28, "department" : "Development", "salary" : 9600 }

{ "_id" : 5, "ename" : "Mark", "age" : 22, "department" : "Development", "salary" : 7800 }

{ "_id" : 6, "ename" : "marry", "age" : 23, "department" : "Planning", "salary" : 6000 }

{ "_id" : 7, "ename" : "hellen", "age" : 32, "department" : "HR", "salary" : 7200 }

{ "_id" : 8, "ename" : "sarah", "age" : 24, "department" : "Development", "salary" : 8400 }

> db.emp.find({"language":{"$exists":true}})

>

$where，用它可以在查询中执行任意的javascript，这样就能在查询中做（几乎）任何事情。为了安全起见，应该严格限制或者消除"$where"语句的使用。

    db.person.find({"$where":function(){

        ...;//这里可以是任意的javascript语句。

    }})

游标, 利用游标可以限制结果的数量，略过部分结果，根据任意键按任意顺序的组合对结果进行各种排序，或者是执行其他的一些强大的操作。

    var cursor = db.person.find();

    while(cursor.hasNext()){

     obj = cursor.next();

     ...;//这里可以做任何事情

     }

常用的shell：

    limit：只返回前面多少个结果。

    db.person.find().limit(2)

    skip：跳过多少个结果后显示剩余的。

    db.person.find().skip(2)

    sort：用于排序。接受一个对象(一组键值对)作为参数，键对应文档的键名，值代表排序的方向。排序的方向可以是1(升序)或者-1(降序)。如果指定了多个键，则按照这些键被指定的顺序逐个排序。

    db.person.find().sort({"name":1,"age":-1})//查询的结果，按照name升序，age降序来排序显示