Exam 70-461 topic 1 question 11 discussion

Actual exam question from Microsoft's 70-461

Question #: 11
Topic #: 1

Your database contains two tables named DomesticSalesOrders and InternationalSalesOrders. Both tables contain more than 100 million rows. Each table has a
Primary Key column named SalesOrderId. The data in the two tables is distinct from one another.
Business users want a report that includes aggregate information about the total number of global sales and total sales amounts.
You need to ensure that your query executes in the minimum possible time.
Which query should you use?

A. SELECT COUNT(*) AS NumberOfSales, SUM(SalesAmount) AS TotalSalesAmount FROM ( SELECT SalesOrderId, SalesAmount FROM DomesticSalesOrders UNION ALL SELECT SalesOrderId, SalesAmount FROM InternationalSalesOrders ) AS p
B. SELECT COUNT(*) AS NumberOfSales, SUM(SalesAmount) AS TotalSalesAmount FROM ( SELECT SalesOrderId, SalesAmount FROM DomesticSalesOrders UNION SELECT SalesOrderId, SalesAmount FROM InternationalSalesOrders ) AS p
C. SELECT COUNT(*) AS NumberOfSales, SUM(SalesAmount) AS TotalSalesAmount FROM DomesticSalesOrders UNION SELECT COUNT(*) AS NumberOfSales, SUM(SalesAmount) AS TotalSalesAmount FROM InternationalSalesOrders
D. SELECT COUNT(*) AS NumberOfSales, SUM(SalesAmount) AS TotalSalesAmount FROM DomesticSalesOrders UNION ALL SELECT COUNT(*) AS NumberOfSales, SUM(SalesAmount) AS TotalSalesAmount FROM InternationalSalesOrders

Show Suggested Answer

Suggested Answer: A 🗳️
Reference:
http://msdn.microsoft.com/en-us/library/ms180026.aspx
http://blog.sqlauthority.com/2009/03/11/sql-server-difference-between-union-vs-union-all-optimalperformance-comparison/

by putriafebriana at Sept. 6, 2020, 12:02 p.m.

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putriafebriana

4 years, 11 months ago

true A

upvoted 1 times

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