Based on the code shown, which query lists the number and name of all customers that are either represented by sales rep 30 or that currently have orders on file, or both???Customer ( CustomerNum, CustomerName, Street, City, State, PostalCode, Balance, CreditLimit, RepNum )
A) SELECT CustomerNum, CustomerName, FROM Customer WHERE RepNum='30' UNION SELECT Customer.CustomerNum, CustomerName, FROM Customer ;
B) SELECT CustomerNum, CustomerName, FROM Customer WHERE RepNum='30' UNION SELECT Customer.CustomerNum, CustomerName, FROM Customer, Orders WHERE Customer.CustomerNum=Orders.CustomerNum ;
C) SELECT CustomerNum, CustomerName, FROM Customer WHERE RepNum='30' WHERE Customer.CustomerNum=Orders.CustomerNum ;
D) SELECT CustomerNum, CustomerName, FROM Customer WHERE RepNum='30' UNION SELECT Customer.CustomerNum, CustomerName, FROM Customer, Orders ;

Question

Quizplus · Accepted Answer

The query in option B selects the CustomerNum and CustomerName from the Customer table where RepNum is equal to 30 and then uses the UNION operator to combine it with a select statement that again selects the CustomerNum and CustomerName from the Customer table where there are corresponding records in the Orders table (which means they currently have orders on file). This satisfies the condition of (a) customers represented by sales rep 30 and (b) customers that currently have orders on file, or both. Option A only selects customers represented by sales rep 30, while option C has a syntax error (WHERE should be replaced with AND or OR) and only considers customers represented by sales rep 30 that also have orders on file. Option D selects all customers and orders, which may include irrelevant records.

Based on the Code Shown, Which Query Lists the Number