persons文档的数据如下: db.persons.find() { _id : 2, name : 2 } { _id : 3, name : 3 } db.persons.update({_id:4},{_id:4,name:4}) WriteResult({ nMatched : 0, nUpserted : 0, nModified : 0 }) db.persons.find() { _id : 2, name : 2 } { _id : 3, n

persons文档的数据如下:

> db.persons.find()
{ "_id" : 2, "name" : 2 }
{ "_id" : 3, "name" : 3 }

> db.persons.update({_id:4},{_id:4,name:4})
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
> db.persons.find()
{ "_id" : 2, "name" : 2 }
{ "_id" : 3, "name" : 3 }

做完update操作，依然看不到_id:4的记录，因为update方法需要一个true指示器，才会对查询不到的记录进行insert操作：

> db.persons.update({_id:4},{_id:4,name:4},true)
WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : 4 })
> db.persons.find()
{ "_id" : 2, "name" : 2 }
{ "_id" : 3, "name" : 3 }
{ "_id" : 4, "name" : 4 }

现有需求，将persons文档中的name为"3"的改成"33"

> db.persons.update({name:"3"},{$set:{name:"33"}},false,true)

false含义:若查不到name:"33"的键值对，则不执行插入操作，true含义:表示是批量更新

为persons增加age:"88"属性

> db.persons.update({name:"4"},{$set:{age:"88"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4", "age" : "88" }

将age加2

> db.persons.update({name:"4"},{$inc:{age:2}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4", "age" : 90 }

将age属性拿走：

> db.persons.update({age:90},{$unset:{age:1}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }

给persons文档增加一条记录，_id为5

> db.persons.insert({_id:5,name:5,books:[]})
WriteResult({ "nInserted" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "name" : 5, "books" : [ ] }

给books数组增加一个元素:"js"和"extjs4.0"

> db.persons.update({_id:5},{$push:{books:"js"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "name" : 5, "books" : [ "js" ] }

> db.persons.update({_id:5},{$push:{books:"extjs4.0"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "name" : 5, "books" : [ "js", "extjs4.0" ] }

创建一个新的classes数组:

> db.persons.update({_id:5},{$push:{classes:"01class"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "name" : 5, "books" : [ "js", "extjs4.0" ], "classes" : [ "01class"
] }

为calsses数组一次增加几个元素:

> db.persons.update({_id:5},{$pushAll:{classes:["02class","03class","04class"]}}
)
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "name" : 5, "books" : [ "js", "extjs4.0" ], "classes" : [ "01class"
, "02class", "03class", "04class" ] }

删除_id是5的记录,并创建一个新的_id是5的记录,使用$addToSet,此命令会检查要添加的元素在数组里面是不是存在，存在就不会再添加，否则会添加:

> db.persons.remove({_id:5})
WriteResult({ "nRemoved" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
> db.persons.insert({_id:5,books:["js"]})
WriteResult({ "nInserted" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "books" : [ "js" ] }
> db.persons.update({_id:5},{$addToSet:{books:"js"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "books" : [ "js" ] }
> db.persons.update({_id:5},{$addToSet:{books:"java"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "books" : [ "js", "java" ] }
> db.persons.update({_id:5},{$addToSet:{books:"mongo"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "books" : [ "js", "java", "mongo" ] }

删除books数组的第一个元素:"js"，使用$pop命令:

> db.persons.update({_id:5},{$pop:{books:-1}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "books" : [ "java", "mongo" ] }
> db.persons.update({_id:5},{$pop:{books:1}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "books" : [ "java" ] }

-1代表第一个元素，1代表最后一个元素

也可以使用pull命令一次删除一个指定的元素:

> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "books" : [ "java", "mongo", "js" ] }
> db.persons.update({_id:5},{$pull:{books:"js"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "books" : [ "java", "mongo" ] }

$pullAll命令可以一次指定多个要删除的元素:

> db.persons.update({_id:5},{$pullAll:{books:["java","mongo"]}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "books" : [ ] }

创建一条新的记录_id为6:

> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "books" : [ ] }
{ "_id" : 6, "books" : [ { "type" : "js", "name" : "extjs4.0" }, { "type" : "db"
, "name" : "mongodb" }, { "type" : "js", "name" : "jquery" } ] }

为type是js的books元素添加pens:"too long"属性，使用.符号一定使用双引号引用

> db.persons.update({"books.type":"js"},{$set:{"books.$.author":"tom"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4, "name" : "4" }
{ "_id" : 5, "books" : [ ] }
{ "_id" : 6, "books" : [ { "type" : "js", "name" : "extjs4.0", "author" : "tom"
}, { "type" : "db", "name" : "mongodb" }]
}

db.persons.update({"books.type":"js"},{$set:{"books.$.pens":"too long"}})

判断数组元素执行插入操作，重复的元素不会被插入第二次:

> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4 }
{ "_id" : 5, "books" : [ "js" ] }

> db.persons.update({_id:5},{$addToSet:{books:{$each:["js","db","java"]}}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.persons.find()
{ "_id" : 2, "name" : "33" }
{ "_id" : 3, "name" : "33" }
{ "_id" : 4 }
{ "_id" : 5, "books" : [ "js", "db", "java" ] }