MongoDB Basic command--database table additions and deletions--traverse the records in the action table

Traversing records in the Update data table

/* * * Add order "  item ID and Item quantity" In order form productiondate  case Data    [{"Productionid": 100001, "Count": 10}, {" Productionid ": 100002," Count ": 9}]***/db. Order . Find (). ForEach (    function(item) {        db. order. Update ({_id:item._id},{$set: {"Productionnum":[{"Productionid": Item.productionid, "Count": Item.count}](}},true)    });

Create a database

 Use database_name

Deleting a database

Db.dropdatabase ()

Create a data table

Db.createcollection ("table name");

Delete a data table

Db. Collection_name. Drop ()

To check the currently selected database using command db

> Dbmydb

If you want to check the database list, use the command show DBS.

> Show Dbslocal      0 . 78125GBtest       0. 23012GB

The basic syntax for the Insert () command is as follows:

/** * * syntax *******/>Db. Collection_name.Insert(document)/** * * example *******/>Db.mycol.Insert({_id:objectid (7df78ad8902c), title:'MongoDB Overview', Description:'MongoDB is no SQL database',    by:'Tutorials Yiibai', URL:'http://www.yiibai.com', Tags:[' MongoDB ', ' database ', ' NoSQL '], likes: -})

Delete a table record

>db. Collection_name.remove (Delletion_critteria)

Querying table Records

>db.mycol.find ({})

Update () Use of updated syntax

>db.mycol. Update ({'title':'MongoDB overview'},{$set: {'  title':'New MongoDB Tutorial'}})  >db.mycol.find ()

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MongoDB Basic command--database table additions and deletions--traverse the records in the action table