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151. View the Exhibit and examine the structure of the CUSTOMERS and CUST_HISTORY tables.

The CUSTOMERS table contains the current location of all currently active customers. The

CUST_HISTORY table stores historical details relating to any changes in the location of all current as well

as previous customers who are no longer active with the company.

You need to find those customers who have never changed their address.

Which SET operator would you use to get the required output?

A. MINUS

B. UNION

C. INTERSECT

D. UNION ALL

Answer: A

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UNION Example The following statement combines the results of two queries with the UNION operator, which eliminates duplicate selected rows. This statement shows that you must match data type (using the TO_CHAR function) when columns do not exist in one or the other table

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UNION ALL Example The UNION operator returns only distinct rows that appear in either result, while the UNION ALL operator returns all rows. TheUNION ALL operator does not eliminate duplicate selected rows

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INTERSECT Example The following statement combines the results with the INTERSECT operator, which returns only those unique rows returned by both queries

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MINUS Example The following statement combines results with the MINUS operator, which returns only unique rows returned by the first query but not by the second

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