Assume a designer is using the UNION operator to combine the results from two tables with identical structure,CUSTOMER and CUSTOMER_2.The CUSTOMER table contains 10 rows,while the CUSTOMER_2 table contains 7 rows.Customers Jenna and Howard are included in the CUSTOMER table as well as in the CUSTOMER_2 table.How many records are returned when using the UNION operator?
A)7
B)10
C)15
D)17

Question

Quizplus · Accepted Answer

The UNION operator combines the results of two queries and removes duplicate rows. Since Jenna and Howard are duplicates, they will be counted only once. Therefore, the total number of unique records returned is 15 (10 from CUSTOMER + 7 from CUSTOMER_2 - 2 duplicates).

Assume a Designer Is Using the UNION Operator to Combine