Sentiment Analysis & Topic Detection from database (MongoDB) based on Tweets

I have crawled a number of tweets (based on different hashtags (more than 200 hashtags crawled)) and have grouped them into 20 different collections in one database. I'm using MongoDB. The fields that I have crawled are: - twitter username - tweet - location - date & time I will give you the data and I want you to help analyze the topic of each tweet and do a sentiment analysis on each tweet. Create new fields inside the database to store these new data. I will need to visualise the data into a website afterwards, thats why I need to analyze positive and negative tweets to create useful stories later.