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SQL for Corrupted Data
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SQL for Corrupted Data

HardSQL · PostgreSQL

Problem

How would you solve a data manipulation problem where the data is corrupted and half the columns have a poor fill rate?

Using the provided raw_claims table, produce a column-level data quality report. Treat blank strings as missing, retain the latest row for duplicate nonblank claim IDs, and identify invalid values using the column rules represented by the sample data.

Output

  1. One row per audited column with column_name, row_count, nonblank_count, fill_rate_pct, invalid_count, poor_fill_rate, and recommendation.
  2. Include all six data columns, order poor-fill columns first, then by fill rate ascending and column name.

Schema

raw_claims
ColumnTypeDescription
raw_row_idPKINTUnique identifier for the raw ingested row
claim_idVARCHAR(30)Claim identifier, potentially duplicated or blank
member_idVARCHAR(30)Member identifier
service_dateVARCHAR(20)Service date stored as raw text
claim_statusVARCHAR(20)Raw claim status
billed_amountVARCHAR(30)Billed amount stored as raw text
diagnosis_codeVARCHAR(20)Diagnosis code expected to match the sample format
ingested_atTIMESTAMPTimestamp when the raw row was ingested
Tablesraw_claims
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