Window Functions SQL Practice | Dataford Interview Questions

Typical SQL questions that involve window functions

Write a PostgreSQL query against account_transactions that returns only posted transactions and calculates the requested per-account metrics.

Output

One row per posted transaction with transaction_id, account_id, transaction_date, amount, sequence_number, amount_rank, and running_total.
Sequence transactions chronologically per account, rank amounts from highest to lowest with ties sharing a rank, and calculate the cumulative amount through each transaction.
Order by account_id, transaction_date, and transaction_id.

account_transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
account_id	VARCHAR(20)	Account associated with the transaction
transaction_date	DATE	Date the transaction occurred
amount	DECIMAL(10,2)	Transaction amount, which may be missing
status	VARCHAR(20)	Transaction processing status

Your question is Window Functions SQL Practice. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Typical SQL questions that involve window functions

Write a PostgreSQL query against account_transactions that returns only posted transactions and calculates the requested per-account metrics.

One row per posted transaction with transaction_id, account_id, transaction_date, amount, sequence_number, amount_rank, and running_total.
Sequence transactions chronologically per account, rank amounts from highest to lowest with ties sharing a rank, and calculate the cumulative amount through each transaction.
Order by account_id, transaction_date, and transaction_id.

account_transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
account_id	VARCHAR(20)	Account associated with the transaction
transaction_date	DATE	Date the transaction occurred
amount	DECIMAL(10,2)	Transaction amount, which may be missing
status	VARCHAR(20)	Transaction processing status

Your question is Window Functions SQL Practice. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.