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TencentDB for MongoDB
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    Reading/Writing Database

    Last updated: 2024-01-15 14:34:08
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      After you connect to the database instance, you can create databases and write data to them.

      Creating a Database

      The syntax to create a MongoDB database is as follows: 
      use DATABASE_NAME
      Create a database named "myFirstDB" and insert a document to it:
      > use myFirstDB
      switched to db myFirstDB
      > db.myFirstDB.insert({"test":"myFirstDB"})
      WriteResult({ "nInserted" : 1 })
      Show the database you created:
      > show dbs
      admin      0.000GB
      config     0.000GB
      local      0.041GB
      myFirstDB  0.000GB

      Creating a Collection

      In MongoDB, you can use the createCollection() method to create a collection. Syntax:
      db.createCollection(name, options)
      Parameter description:
      name: the name of the collection to create
      options: (optional) options of memory size and index
      options Field
      Type
      Description
      capped
      BOOL
      Whether to set a maximum size in bytes for the collection. Valid values: true (the size field must be specified), false (default)
      autoIndexId
      BOOL
      Whether to automatically create an index on the \\_id field. Valid values: true, false (default)
      size
      number
      The maximum size in bytes of the collection
      max
      number
      The maximum number of documents in the collection
      Create a collection named "FirstCol" in the myFirstDB database:
      > use myFirstDB
      switched to db myFirstDB
      > db.createCollection("FirstCol")
      {
              "ok" : 1,
              "$clusterTime" : {
                      "clusterTime" : Timestamp(1634821900, 2),
                      "signature" : {
                              "hash" : BinData(0,"WFu7yj8wjeUBWG3b+oT84Q8wIw8="),
                              "keyId" : NumberLong("6990600483068968961")
                      }
              },
              "operationTime" : Timestamp(1634821900, 2)
      }
      Show the collection you created:
      > show collections
      FirstCol
      The following sample shows that the FirstCol collection you created can have up to 10,000 documents whose total size cannot exceed 6,142,800 bytes.
      > db.createCollection("FirstCol", { capped : true, autoIndexId : true, size : 6142800, max : 10000 } )
      {
              "note" : "the autoIndexId option is deprecated and will be removed in a future release",
              "ok" : 1,
              "$clusterTime" : {
                      "clusterTime" : Timestamp(1634821879, 1),
                      "signature" : {
                              "hash" : BinData(0,"EuIbp2fu9Yh38HOBHLgYqljdKaE="),
                              "keyId" : NumberLong("6990600483068968961")
                      }
              },
              "operationTime" : Timestamp(1634821879, 1)
      }

      Inserting a Document

      In MongoDB, you can use the insert() or save() method to insert a document to a collection, as shown below:
      > db.FirstCol.insert({name:"Jane Smith",sex:"Female",age:25,status:"A"})
      WriteResult({ "nInserted" : 1 })
      Show the document inserted to the collection:
      > db.FirstCol.find()
      { "_id" : ObjectId("61716957a6fe1ef4d7eae979"), "name" : "Jane Smith", "sex" : "Female", "age" : 25, "status" : "A" }
      You can use db.collection.insertMany() to insert one or more documents to a collection, as shown below:
      db.collection.insertMany(
       [ <document 1> , <document 2>, ... ]
       )
      Sample:
      > db.FirstCol.insertMany([{name:"Mary Smith",sex:"Female",age:25,status:"A"},{name:"John White",sex:"Male",age:26,status:"B"},{name:"Michael White",sex:"Male",age:26,status:"A",groups:["news","sports"]}])
      {
      
            "acknowledged" : true,
            "insertedIds" : [
                    ObjectId("617282a3a4bb72d733b5c6d7"),
                    ObjectId("617282a3a4bb72d733b5c6d8"),
                    ObjectId("617282a3a4bb72d733b5c6d9")
            ]
      }

      Updating a Database

      In MongoDB, you can use update() to update documents in a collection.
      Update the data in the FirstCol collection where name is Mary Smith:
      > db.FirstCol.update({name:"Mary Smith",sex:"Female",age:25,status:"A"},{$set:{'age':28}})
      WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
      Show the result:
      > db.FirstCol.find().pretty()
      {
              "_id" : ObjectId("618904b6258a6c38daf13abd"),
              "name" : "Mary Smith",
              "sex" : "Female",
              "age" : 28,
              "status" : "A"
      }
      {
              "_id" : ObjectId("618904b6258a6c38daf13abe"),
              "name" : "John White",
              "sex" : "Male",
              "age" : 26,
              "status" : "B"
      }
      {
              "_id" : ObjectId("618904b6258a6c38daf13abf"),
              "name" : "Michael White",
              "sex" : "Male",
              "age" : 26,
              "status" : "A",
              "groups" : [
                      "news",
                      "sports"
              ]
      }

      Deleting a Database

      In MongoDB, you can use remove() to delete documents from a collection, as shown below:
      > db.FirstCol.remove({name:"Mary Smith",sex:"Female",age:28,status:"A"})
      WriteResult({ "nRemoved" : 1 })
      Show the result:
      > db.FirstCol.find().pretty()
      {
              "_id" : ObjectId("618904b6258a6c38daf13abe"),
              "name" : "John White",
              "sex" : "Male",
              "age" : 26,
              "status" : "B"
      }
      {
              "_id" : ObjectId("618904b6258a6c38daf13abf"),
              "name" : "Michael White",
              "sex" : "Male",
              "age" : 26,
              "status" : "A",
              "groups" : [
                      "news",
                      "sports"
              ]
      }

      References

      For more information, see MongoDB official documentation.
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