Question

I have a table in MySQL which has following columns

Table – Reviews

Review_Id
Business_Id
Title
Description
Useful_Count

A particular business_id (foreign key) can have many reviews. What I want is to extract this information from DB given a set of business Ids

1. Total review count for each business Id
2. The top review (title and description mainly) for each business Id (Top review would be the one having highest number of useful_counts.

Is it possible to get both the information using a single SQL query?

Answer 1

Try this:

SELECT r.Business_Id, t.c AS 'Number of Reviews', 
    r.Title, r.Description, t.max_useful_count 
FROM Reviews r
JOIN (SELECT Business_Id, COUNT(Business_Id) AS c, 
        MAX(Useful_Count) AS max_useful_count
      FROM Reviews
      WHERE r.Business_Id IN (...)
      GROUP BY Business_Id) as t
  ON r.Business_Id = t.Business_Id
  AND r.Useful_Count = t.max_useful_count