added mongo notepad

mongo.md

@@ -0,0 +1,38 @@
+` show dbs ` list all the databases which is having any collection(table)
+
+` use <database-name> ` switched to database with name <database-name>. If there is no database with given name, creates one and switched to it.
+
+` db ` outputs the currently used database
+
+` db.createCollection(<collection-name>) ` creates a collection
+
+` show collections ` list the collections in current selected database
+
+` db.<collection_name>.insert({<js_object>}) ` inserts the object in collection
+
+` db.<collection_name>.insertMany([{<js_objects>}]) ` inserts the objects in collection
+
+` db.<collection_name>.find() ` lists the object in collection
+
+` db.<collection_name>.find({ key: value }) ` lists the object in collection which matches given key value pair(words(key-value pair) are case sensitive)
+
+` db.<collection_name>.find().pretty() ` lists the objects in collection in more readable format
+
+` db.<collection_name>.find().sort({ key: <value>}) ` lists the objects in collection in sorted form. value{ 1: asc, -1: desc}
+
+` db.<collection_name>.find().count() ` show the count of objects in collection
+
+` db.<collection_name>.find().limit(<quantity>) ` show the list of objects in collection by given quantity
+
+` db.<collection_name>.find().forEach(<function>) ` list of objects in collection based on given object
+
+` db.<collection_name>.findOne({<key-value pair condition>}) ` show the first object in collection; condition is optional
+
+` db.<collection_name>.update() ` update the object. 
+- `.update({<mathcing_condition>}, {<updated_value>}, {upsert: true/false}) ` If the upsert value is true then the new object is created if there is no object with given matching condition otherwise ignores
+  - ` <update_value> ` If the object is given directly, then it will override the content of previous object
+  - ` $set: <update_value> ` The object will be updated with prevoious values intact
+  - ` $inc: {key: value} ` the object will be updated with incrementing the value of key by <value>
+  - ` #rename: { old_key: new_key } ` the old key will be renamed to new key
+
+` db.<collection_name>.remove({<matching_condition>}) ` remove the object from collection