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Running Total Reviews With Window Functions

MediumSQL · PostgreSQL00:00
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Your question is Running Total Reviews With Window Functions. Start with the requirements and the two tables on the right.

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Problem

Yelp's Data Science team wants to monitor recent review activity for each Yelp user. Write a PostgreSQL query that reports the number of reviews each user submitted on each active review date and the user's trailing 30-day review total.

Requirements

  1. Join users to reviews and exclude reviews that do not belong to a registered user.
  2. Aggregate multiple reviews by the same user on the same calendar date.
  3. Use a window function partitioned by user and ordered by review date. The trailing window includes the current date and the preceding 29 calendar days.
  4. Return results ordered by user and review date.

Schema

users
ColumnTypeDescription
user_idPKINTEGERUnique Yelp user identifier
display_nameVARCHAR(100)User's public Yelp display name
reviews
ColumnTypeDescription
review_idPKINTEGERUnique review identifier
user_idINTEGERYelp user who authored the review
review_dateDATEDate the review was published
review_textTEXTReview content
Tablesusersreviews
Your solutionPostgreSQL
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