**Why STUFF + FOR XML PATH:** SQL Server pattern for string aggregation pre-2017. Builds comma-separated lists, XML fragments. Replaced by STRING_AGG in modern SQL. **Syntax:** STUFF(string, start, length, replace)—replaces chars. Combined with FOR XML PATH(''): concatenates...
This medium-level Python/Coding question appears frequently in data engineering interviews at companies like NAB. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (sql) will help you answer variations of this question confidently.
Break this problem into components. Identify the core trade-offs involved, then walk the interviewer through your reasoning step by step. Demonstrate awareness of edge cases and production considerations - this is what separates good answers from great ones.
Why STUFF + FOR XML PATH: SQL Server pattern for string aggregation pre-2017. Builds comma-separated lists, XML fragments. Replaced by STRING_AGG in modern SQL.
Syntax: STUFF(string, start, length, replace)—replaces chars. Combined with FOR XML PATH(''): concatenates rows into string; STUFF removes leading comma.
Scalability: FOR XML PATH scans all rows—O(n). For large aggregations (100K+ rows per group), consider CLR aggregate or application-layer concatenation. STRING_AGG is native, optimized.
SELECT STUFF((SELECT ','+name FROM t FOR XML PATH('')),1,1,'')
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Analyze My Answer — FreeAccording to DataEngPrep.tech, this is one of the most frequently asked Python/Coding interview questions, reported at 1 company. DataEngPrep.tech maintains a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.