I am new to Amazon Dynamo DB, I have created a user table and address table.and I want to retrieve all users with their particular address as I have assigned user_id in address table to each address. So how can I get user info with address with one query rather than querying both table and merge after. Is their any way like in MySQL we can use JOIN?
Dynamodb is not meant for these types of queries; especially aggregation queries are not ideal. DynamoDB is mainly good for fast lookups for predefined access patterns (e.g. get all items in shopping cart for user ID X).
Since addresses are unique properties of users, you might be able to add an attribute to the user ID table. So basically you have one table with all user data and their properties, including address, that you can query by user ID.
If you need to support different queries I'd suggest you note them all down first before deciding on your data model. (E.g. get all users and sort by last name, get all users living in city X). If the data model in dynamodb is too complex to support all these access patterns you might need to change to a SQL-like db instead.
Edit: note that there are ways to model relationships in dynamodb but they are not trivial. For some examples see the link below. But as suggested above, first define your access patterns before deciding on your data model. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/bp-modeling-nosql-B.html