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Write a Merge Statement for SCD Type 2.

SQLeasy0.4 min readPremium
Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
EY
Key Concepts Tested
snowflakesql
Expert AnswerPremium
80 wordsInterview-ready
MERGE INTO dim_customer t USING staging s ON t.customer_id = s.customer_id AND t.is_current = 1 WHEN MATCHED AND t.hash != s.hash THEN UPDATE SET t.is_current = 0, t.end_date = CURRENT_DATE INSERT (customer_id, attr1, attr2, effective_date, end_date, is_current) VALUES (s.customer_id, s.attr1, s.attr2, CURRENT_DATE, '9999-12-31', 1) WHEN NOT MATCHED THEN INSERT ... **Why hash**: Efficient change detection; avoids comparing every column....
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