Mongo DB first take

Testing new waters. My first NoSQL db was InfluxDB. It is a Time based No SQL type db. 

This time I wanted to taste the all famous MongoDB. I want to keep the basics handy. So I write as I learn.

Basic Commands ☝

Launch MongoDB:

~ mongo

See existing databases

show dbs

Create a database

use db_name

Return: Creates and switches to it. 

Note: It won't show in db list unless we create at least one entry (a collection)

Use a database

use db_name

Returns: switched to db db_name

See all  collections in that database

show collections

Drop a Database

db.dropDatabase()

Create a collection

db.createCollection("some_name")

Drop a collection

db.collection_name.drop()

Returns : true

Insert data into collection and verify

db.collection_name.insert({key1:value1, ......})

Let's try adding one more. Something to note here. You can use find to query. 

You can use pretty() to see a well formatted output.

Querying Data

In this, we will explore various ways to find data.

Methods available: find(), findOne()

* find() is == all()

* find({key:value}) == filter(key=value) 

To find exact data matching results, we just mention the key and value 

({key:value}) 

If not exact but some condition :

LT

    ( { key: $lt:value } ) Note: spaces are only to show clearly.

GT 

    ( { key: $gt:value } ) 

LTE 

    ( { key: $lte:value } ) 

GTE

   ( { key: $gte:value } ) 

NE

   ( { key: $ne:value } ) 

IN (Value in array)

   ( { key: $in:value } ) 

NIN  

   ( { key: $nin:value } ) 

Example Queries:

1. Find user by exact age and greater than.

2. Find from a list of choices. Here , I provide a list of options. All the ones matching exactly are listed.

3. We can combine filters with AND and OR

It can get pretty ugly, thats why I posted the first one formatted. 

4.  NOR