Left Join vs Inner Join | Dataford Interview Questions

Can you explain the difference between a left join and an inner join in a practical scenario for investment data?

Use the tables below to compare trade records with account reference data. Write a SQL query that returns all trades with their account status when available, and keeps trades even when no matching account exists.

Output

One row per trade.
Columns: trade_id, account_id, trade_date, trade_amount, account_status.
Include trades with no matching account, and show NULL for account_status in those rows.
Ignore rows where trade_amount is NULL.
Sort by trade_date ascending, then trade_id ascending.

Schema

trades

Column	Type	Description
trade_idPK	INT	Unique trade identifier
account_id	INT	Account identifier associated with the trade
trade_date	DATE	Trade execution date
trade_amount	NUMERIC(12,2)	Trade notional amount

accounts

Column	Type	Description
account_idPK	INT	Unique account identifier
account_status	VARCHAR(20)	Current account status

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Problem