Access token is a Jwt token that JWT gives us when we are first time login if our login was success then jwt gives us tow token one is Access Token and another is Refresh Token. Access Token usually use when we have to load secure information from database that time we add this Access token in Our API headers if the Access tacket is valid thn only server give that secure dada otherwise it send error;
When a Access token is expired then we have to send the server Refresh token then server send us valid access Token.
When Refresh Token is also Expired then user have to re login for generate new access token and refresh token
We store Access and Refresh token in client side because we have to send them in your api call header froe secure our data from unauthorized User.
The full from of SQL is Structured Query Language. It store data in tabular from with fixed Rows and column. It's used in relational database. for this reason its decrees the data duplication
It's highly performed in real time database system. It use JSON type data with KEY VALUE pairs table with rows and dynamic columns. It is more flexible then SQL Database system.
Express js is a Node js Fretwork and Nest Js is also Node js Fretwork and it use express js HTTP fretwork by default. And also nest js support all that things in express js.
Mongodb aggregation is a system where we can process our document like sort, limit,skip,match etc. Mongo DB aggregation pipeline use $ symbol for operation like- $sort, $limit etc.