SQL Print Duplicates | Dataford Interview Questions

Write an SQL query to print the duplicates from a table.

Use the client_records table. Treat records with the same non-null account_reference as duplicates. Return every record belonging to a duplicated account reference, excluding null references.

Output

One row per duplicated record
Columns: record_id, account_reference, source_system, loaded_at, and duplicate_count
Sort by account_reference ascending, then record_id ascending

Schema

client_records

Column	Type	Description
record_idPK	INT	Unique record identifier
account_reference	VARCHAR(20)	Reference used to identify an account
source_system	VARCHAR(30)	System that supplied the record
loaded_at	DATE	Date the record was loaded

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