What does the union operator do

Provide 1 reference. Answer the following discussion question:

A relational Database Model allows database users to analyze data thoroughly. To accomplish this, advanced commands such as UNION and INTERSECT may be used. Describe a business scenario where a UNION relational set operator may be used to merge two similar data sets. Within the context of your business scenario, analyze the analysis and data consistency advantages of using a UNION operator rather than simply merging two data sets into one result table.

Suppose you are tasked with finding common data elements amongst various data sets. Specify how an INTERSECT operator may assist you in accomplishing this task. Construct a query that can perform the same function as the INTERSECT operator without using the "INTERSECT" syntax within the query.

Respond to this Discussion with at least 1 paragraph:

"I choose to answer this discussion thread using some work-related examples of mine. I believe by doing so will allow people to see the real-world application of the operators specified.

I work for a direct marketing company and we do a lot of data processing and mailing for various clients. Recently I was tasked with an assignment where one of our clients had multiple lists (three to be precise). They only wanted one of their marketing packages mailed to each client on their list. So let’s say for example I Emmanuel was on the 2019, 2018 and 2017 list. They did not want to mail to me 3 times. They only wanted me to receive a single packet. In this case a simple union on the three lists yielded a result set free of all duplicates. Had I simply merged the data, then someone like me would have gotten multiple packages rather than the one package intended. From a business standpoint would have also been a waste.

Again, another work scenario regarding intersect. The client had two lists. One list had customers who listen to and donated financially to Public radio. The other had customers who listen to and donated to public TV. The client only wanted their marketing package going to people who donated to both Radio and TV. In this case a simple intersect was able to do the trick.

So if I wrote a query using intersect it would look like the following:

Select customer_ID, prefix, first_name, last_name, address_line1, address_line2, city, state, zip from TableTV

Intersect

Select customer_ID, prefix, first_name, last_name, address_line1, address_line2, city, state, zip from TableFM

I could also write this query without intersect by using an inner join as follows:

Select TV.customer_ID, TV.prefix, TV.first_name, TV.last_name, TV.address_line1, TV.address_line2, TV.city, TV.state, TV.zip from TableTV TV

Join TableFM FM ON FM.customer_ID = TV.customer_ID

I could also use a subquery by doing the following:

Select customer_ID, prefix, first_name, last_name, address_line1, address_line2, city, state, zip from TableTV WHERE customer_ID IN (Select customer_ID from TableFM)

There are scenarios where the ID might not be the same with some clients. In this case the ID’s were the same. But let’s say if the ID’s were different then there are algorithms we run on the name and address fields to create a keyline which can then be used for matching purposes. Will however keep this simple as in both cases the job was very simple."