enrique_aeo
asked on
sql server 2012 - Using Derived Tables
hi experts
i do not understand thedifference between two querys
-- Select this query and execute it to show internal column aliases
SELECT orderyear, COUNT(DISTINCT custid) AS cust_count
FROM (SELECT YEAR(orderdate) AS orderyear, custid
FROM Sales.Orders) AS derived_year
GROUP BY orderyear;
-- Select this query and execute it to show external column aliases
SELECT orderyear, COUNT(DISTINCT custid) AS cust_count
FROM (SELECT YEAR(orderdate), custid
FROM Sales.Orders) AS derived_year(orderyear, custid)
GROUP BY orderyear;
query.png
i do not understand thedifference between two querys
-- Select this query and execute it to show internal column aliases
SELECT orderyear, COUNT(DISTINCT custid) AS cust_count
FROM (SELECT YEAR(orderdate) AS orderyear, custid
FROM Sales.Orders) AS derived_year
GROUP BY orderyear;
-- Select this query and execute it to show external column aliases
SELECT orderyear, COUNT(DISTINCT custid) AS cust_count
FROM (SELECT YEAR(orderdate), custid
FROM Sales.Orders) AS derived_year(orderyear, custid)
GROUP BY orderyear;
query.png
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SOLUTION
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