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marta-krzyk-dev/Union VS Union All.sql

Created February 21, 2019 10:40
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SQL: UNION vs UNION ALL
Raw
Union VS Union All.sql
--UNION ALL allows duplicates, whereas UNION does not (returns only distinct rows)
SELECT CustomerName FROM orders
UNION
SELECT CustomerName FROM customers;
--Result:
--Mary
--John
--Bill
--Anton
SELECT CustomerName FROM orders
UNION ALL
SELECT CustomerName FROM customers;
--Result:
--Mary
--Mary
--Mary
--Mary
--John
--John
--Bill
--Bill
--Anton
--Anton
--Anton
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