【MonogoDB】The high update operation of MongoDB

In the last four blog, we talked about the high query operation of mongodb. Now in this blog let‘s know about the high update operation about monodb.

1. Save

as for save(), whose function is to update the existing record and to create the new record.
grammar: db.mycollection.save(x);

2. General Operation

2.1 $inc 

grammar: { $inc : { field : value } }
function： add the value to the certain field. 
example: 

2.2 $Set and $unset

{ $set : { field : value } }  /  { $unset : { field : 1 } } 
function: set the field value, if the field does not exist, then add the new field, and value will support all the type. 

2.3 $push, $pushAll,$addToSet

{ $push : { field : value }  } 
function: if the field is a existing arry, this function will add the value to the end.  if filed doesnot exist, it will add the new field, and then set the field value.  if field do exists but not array, it will throw error. 
$pushAll:  { $pushAll : {field : value_array } } 
this function is the same as $push, but only the value_array is array.
$addToSet: { $addToSet : { field : value } }

2.4   $pop and $pull $pullAll

2.5 $rename

{ $rename : { old_friend_name: new_field_name}}