**Architectural Logic**: Normalization ensures integrity; SCD-1/3 handles dimension updates. **Normalization**: 1NF–3NF; reduces redundancy; consistency; efficient updates. **SCD-1**: `UPDATE dim SET col = new_val WHERE key = X`. **SCD-3**: `UPDATE dim SET prev_col = col, col =...
This easy-level SQL question appears frequently in data engineering interviews at companies like Meesho. 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.
Start by clearly defining the core concept being asked about. Interviewers want to see that you understand the fundamentals before diving into implementation details. Structure your answer with a definition, then explain the practical application with a concise example.
Architectural Logic: Normalization ensures integrity; SCD-1/3 handles dimension updates. Normalization: 1NF–3NF; reduces redundancy; consistency; efficient updates. SCD-1: UPDATE dim SET col = new_val WHERE key = X. SCD-3: UPDATE dim SET prev_col = col, col = new_val, updated = NOW() WHERE key = X. MERGE: MERGE dim USING staging ON dim.key = staging.key WHEN MATCHED THEN UPDATE SET .... Best Practice: Surrogate keys; track updates; SCD-1 for non-critical; SCD-3 when limited history needed.
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Analyze My Answer — FreeAccording to DataEngPrep.tech, this is one of the most frequently asked SQL 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.