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Compare Expected vs Actual After Migration
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Compare Expected vs Actual After Migration

HardSQL · PostgreSQL

Problem

Write a SQL query to compare expected versus actual data after a migration.

Compare every record key in the expected and actual datasets. The result should identify matching records, changed values, records missing from the actual dataset, and unexpected actual records. Comparisons must treat two NULL values as equal.

Output

  1. One row per distinct record key.
  2. Columns: record_key, expected and actual values, and comparison_result.
  3. Include match, mismatch, missing_actual, and unexpected_actual results.
  4. Order by record_key ascending.

Schema

expected_migration
ColumnTypeDescription
record_keyPKVARCHAR(20)Stable identifier expected after migration
statusVARCHAR(20)Expected record status
amountNUMERIC(12,2)Expected monetary value
updated_atDATEExpected last update date
actual_migration
ColumnTypeDescription
record_keyPKVARCHAR(20)Stable identifier produced by migration
statusVARCHAR(20)Actual migrated record status
amountNUMERIC(12,2)Actual migrated monetary value
updated_atDATEActual migrated last update date
Tablesexpected_migrationactual_migration
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CodePostgreSQL
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