Delete vs Truncate vs Drop | Dataford Interview Questions

Explain the difference between DELETE, TRUNCATE, and DROP in SQL.

Use PostgreSQL-compatible SQL to demonstrate the expected effect of each operation without permanently modifying the supplied sample tables. Report the affected rows, remaining rows, and whether the table object remains available.

Output

One row for each operation: DELETE, TRUNCATE, and DROP
Columns: operation, rows_affected, rows_remaining, and object_state
Order rows in the sequence DELETE, TRUNCATE, DROP; use NULL for values that do not apply

Schema

delete_demo

Column	Type	Description
idPK	INT	Unique row identifier
marker	VARCHAR(20)	Value used to identify rows for deletion
payload	VARCHAR(100)	Sample row content

truncate_demo

Column	Type	Description
idPK	INT	Unique row identifier
marker	VARCHAR(20)	Descriptive row marker
payload	VARCHAR(100)	Sample row content

drop_demo

Column	Type	Description
idPK	INT	Unique row identifier
marker	VARCHAR(20)	Descriptive row marker
payload	VARCHAR(100)	Sample row content

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Problem