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SQL: Monthly Complaints With MoM

MediumSQL · PostgreSQL00:00
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Your question is SQL: Monthly Complaints With MoM. Start with the requirements and the two tables on the right.

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Problem

Write a SQL query to calculate monthly service complaints by site, including the month-over-month change in complaints.

Use the service complaints data across all months represented by complaint dates. Include every site for every month in that range, including months with zero complaints. The first month for each site should have a NULL prior-month value and NULL change.

Output

  1. One row per site and calendar month
  2. Columns: site_name, month, complaint_count, previous_month_complaints, mom_change
  3. Include all sites, including sites with no complaints
  4. Order by site_name, then chronological month

Schema

sites
ColumnTypeDescription
site_idPKINTUnique facility identifier
site_nameVARCHAR(100)Facility name
regionVARCHAR(50)Operational region
service_complaints
ColumnTypeDescription
complaint_idPKINTUnique complaint identifier
site_idINTSite associated with the complaint
complaint_dateDATEDate the complaint was received
categoryVARCHAR(80)Complaint category
Tablessitesservice_complaints
Your solutionPostgreSQL
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