Validate Data Integrity | Dataford Interview Questions

What steps would you take to ensure the integrity of your data before analysis?

Use the users and transactions tables to identify transaction records with missing user references, invalid amounts, unsupported or missing statuses, invalid dates, or users whose email appears more than once.

Output

One row per transaction, with transaction_id, integrity_status, and issue_details.
Mark rows as valid only when no listed issue exists; otherwise mark them as invalid.
Order by transaction_id ascending.

Schema

users

Column	Type	Description
user_idPK	INT	Unique user identifier
full_name	VARCHAR(100)	User's full name
email	VARCHAR(255)	User email address

transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
user_id	INT	Referenced user identifier
amount	NUMERIC(12,2)	Transaction amount
status	VARCHAR(20)	Transaction status
transaction_date	DATE	Transaction date

Your question is Validate Data Integrity. Start with the requirements and the two tables in the Question tab.

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Problem