mongodb update statement

MongoDB using  update ()  and  save ()  method to update the collection of documents:

update () method:

update () method is used to update the existing document. Syntax is as follows:

db.collection.update(
   <query>,
   <update>,
   {
     upsert: <boolean>,
     multi: <boolean>,
     writeConcern: <document>
   }
)

Parameter Description:

• Query  : query update, similar to the back where within sql update query.
• Update  : Update objects and some of the newer operators (e.g., $, $ inc is ...) and the like, may be understood as a set behind the sql update query
• the upsert  : Alternatively, this parameter means that, if the record does not exist in the update, whether to insert objNew, true inserted, the default is false, not inserted (equivalent to insertion).
• Multi  : Optional, mongodb default is false, only updating the first record found, if this parameter is true, according to the conditions put many records to check out all the updates.
• writeConcern  : Optional, throw-level exception.

Examples

We insert the following data set in col:

> db.col.insert ({ 
    title: 'Tutorial MongoDB', 
    Description: 'MongoDB is a database Nosql', 
    by: 'novice tutorial', 
    URL: 'http://www.runoob.com', 
    Tags: [ ' MongoDB ',' Database ',' the NoSQL '], 
    Likes: 100 
})

　　

Then we have to update the title by the update () method (title):

>db.col.update({'title':'MongoDB 教程'},{$set:{'title':'MongoDB'}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })   # 输出信息
> db.col.find().pretty()
{
        "_id" : ObjectId("56064f89ade2f21f36b03136"),
        "title" : "MongoDB",
        "description" : "MongoDB 是一个 Nosql 数据库",
        "by" : "菜鸟教程",
        "url" : "http://www.runoob.com",
        "tags" : [
                "mongodb",
                "database",
                "NoSQL"
        ],
        "likes" : 100
}
>

We can see the title (title) from the original "MongoDB Tutorial" Update to "MongoDB."

The above statement will only modify a document found in the first, if you want to modify the same document and more, you need to set multi parameter to true.

>db.col.update({'title':'MongoDB 教程'},{$set:{'title':'MongoDB'}},{multi:true})

save () method

save () method to replace the existing document by the incoming document. Syntax is as follows:

db.collection.save(
   <document>,
   {
     writeConcern: <document>
   }
)

Parameter Description:

• the Document  : document data.
• writeConcern  : Optional, throw-level exception.

Examples

The following examples we replace the document data _id as 56064f89ade2f21f36b03136 of:

>db.col.save({
    "_id" : ObjectId("56064f89ade2f21f36b03136"),
    "title" : "MongoDB",
    "description" : "MongoDB 是一个 Nosql 数据库",
    "by" : "Runoob",
    "url" : "http://www.runoob.com",
    "tags" : [
            "mongodb",
            "NoSQL"
    ],
    "likes" : 110
})

After the replacement is successful, we can () command to view the data by replacing the find

>db.col.find().pretty()
{
        "_id" : ObjectId("56064f89ade2f21f36b03136"),
        "title" : "MongoDB",
        "description" : "MongoDB 是一个 Nosql 数据库",
        "by" : "Runoob",
        "url" : "http://www.runoob.com",
        "tags" : [
                "mongodb",
                "NoSQL"
        ],
        "likes" : 110
}
>　

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More examples

Only the first record update: 
db.col.update ({ "COUNT": {$ gt:. 1}}, {$ SET: { "test2": "the OK"}}); 
total update: 
db.col.update ({ "count": {$ gt: 3}}, {$ set: { "test2": "OK"}}, false, true); 
add only the first: 
db.col.update ({ "COUNT" : {$ gt: 4}} , {$ set: { "test5": "OK"}}, true, false); 
add all added to the list: 
db.col.update ({ "COUNT": {$ gt:. 5 }}, {$ set: { "test5": "OK"}}, true, true); 
total update: 
db.col.update ({ "COUNT": {$ gt: 15}}, {$ inc is: { "count": 1}}, false, true); 
update only the first record: 
db.col.update ({ "COUNT": {$ gt: 10}}, {$ inc is: { "COUNT":}. 1 }, false, false);