sql / expert
Snippet
Multi-set Difference with EXCEPT ALL
EXCEPT ALL performs a multiset difference between two result sets. Unlike EXCEPT, which removes all duplicates, EXCEPT ALL subtracts the count of values in the second set from the first. If 'Product A' appears 5 times in the first set and 2 times in the second, EXCEPT ALL will return 'Product A' 3 times.
snippet.sql
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SELECT product_id FROM inventory_2023EXCEPT ALLSELECT product_id FROM inventory_2024;
Breakdown
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SELECT product_id FROM inventory_2023
Retrieves all product IDs from the first source, including duplicates.
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EXCEPT ALL
Subtracts matching occurrences from the second set without performing a distinct operation.
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SELECT product_id FROM inventory_2024
Retrieves the IDs from the second source that will be 'removed' from the first.