SQL Anti-Join Without Nested Queries | Dataford Interview Questions

Write a query to list the rows present in a first table but not in a second table without using any nested query.

Use reference_code to determine whether a row in first_table exists in second_table. Rows with a null reference code should be treated as having no match.

Output

Return one row per unmatched row from first_table.
Include row_id, reference_code, and row_description.
Sort by row_id in ascending order.

Schema

first_table

Column	Type	Description
row_idPK	INT	Unique identifier for a row in the first table
reference_code	VARCHAR(20)	Code used to find a corresponding row in the second table
row_description	VARCHAR(100)	Description associated with the first-table row

second_table

Column	Type	Description
row_idPK	INT	Unique identifier for a row in the second table
reference_code	VARCHAR(20)	Code that may correspond to a first-table row
row_description	VARCHAR(100)	Description associated with the second-table row

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Problem