¨ Subquery in FROM clause must be given a name
🞑 Many DBMSes also require attributes to be named
SELECT customer_city, num_customers
FROM (SELECT customer_city, COUNT(*)
FROM customer GROUP BY customer_city)
AS counts (customer_city, num_customers)
WHERE num_customers > 2;
🞑 Nested query is called counts, and specifies two attributes
🞑 Syntax varies from DBMS to DBMS…
- MySQL requires a name for derived relations, but doesn’t allow attribute names to be specified.
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