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Return exactly customer_id, old_tier, new_tier, old_valid_from, old_valid_to, new_valid_from, and new_valid_to for current history rows whose staged attributes changed.
Result columns · in this order
customer_idold_tiernew_tierold_valid_fromold_valid_tonew_valid_fromnew_valid_toHow to approach it
Join clean_stage to dim_customer_history where is_current = 1, then compute the close and open boundaries.
Sample input
| customer_id | tier | valid_from | valid_to | is_current |
|---|---|---|---|---|
| 101 | silver | 2025-01-01 | 9999-12-31 | 1 |
| 104 | gold | 2026-02-20 | 9999-12-31 | 1 |
| 105 | bronze | 2025-12-01 | 9999-12-31 | 1 |
3 rows — all rows shown.
| customer_id | tier | updated_at |
|---|---|---|
| 101 | gold | 2026-03-05 10:00:00 |
| 104 | platinum | 2026-03-05 12:30:00 |
| 105 | bronze | 2026-03-05 08:00:00 |
3 rows — all rows shown.
Expected output
| customer_id | old_tier | new_tier | old_valid_from | old_valid_to | new_valid_from | new_valid_to |
|---|---|---|---|---|---|---|
| 101 | silver | gold | 2025-01-01 | 2026-03-04 | 2026-03-05 | 9999-12-31 |
| 104 | gold | platinum | 2026-02-20 | 2026-03-04 | 2026-03-05 | 9999-12-31 |
2 rows — all rows shown.
Constraints
Use the latest staged non-deleted row per customer. Join only dim_customer_history rows where is_current = 1. Close the old row one day before the staged updated_at date, open the new row on updated_at's date, and order by customer_id.
Expected skills
SCD2 change detection, validity ranges, and current-row history reasoning.
Submit for review to find out what your query gets right, what it gets wrong, and how it compares with the best working query for this exercise.
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