SQL · Intermediate · 35 min
Accounts that disagree after migration
Find missing, extra, and changed records even when counts match.
Task
Compare source_accounts and target_accounts after a migration. Normalize account IDs by trimming spaces and converting to lower case. Report every missing, target-only, or changed balance.
Requirements
- Both tables have account_id and balance_cents. IDs are unique after normalization.
- A null balance is a legitimate unknown value. Null equals null for reconciliation, but differs from a known balance.
- Return account_id and issue, using missing, target_only, or changed. Order by account_id.
- Equal total balances or row counts do not prove that records match. Use SQLite.
ReconciliationNULL handlingSet comparison
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