Querying Null Entries | Dataford Interview Questions

Your question is Querying Null Entries. Start with the requirements and the two tables on the right.

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

Problem

First Trust Capital Management is reviewing client account data before producing advisor and regulatory reports. Write a PostgreSQL query that returns every account with one or more missing required values or without a matching advisor record.

Requirements

Use a LEFT JOIN so accounts are retained even when their advisor is missing.
Identify rows where risk_profile or tax_status is NULL, or where the account has no matching advisor.
Return the account ID, client name, advisor name, and a comma-separated description of the missing entries.
Sort the results by account_id ascending.

Schema

client_accounts

Column	Type	Description
account_idPK	INT	Unique client account identifier
client_name	VARCHAR(100)	Client or household name
advisor_id	INT	Assigned advisor identifier
risk_profile	VARCHAR(30)	Investment risk classification
tax_status	VARCHAR(30)	Tax treatment of the account
opened_on	DATE	Account opening date

advisors

Column	Type	Description
advisor_idPK	INT	Unique advisor identifier
advisor_name	VARCHAR(100)	Advisor's full name
team_name	VARCHAR(80)	Advisor team