Discuss CompTIA DS0-001 Exam Topic 1 Question 53

A database administrator is migrating the information in a legacy table to a newer table. Both tables contain the same columns, and some of the data may overlap.

Which of the following SQL commands should the administrator use to ensure that records from the two tables are not duplicated?

AUNION

BJOIN

CIINTERSECT

DCROSS JOIN

Suggested Answer: A

The SQL command that the administrator should use to ensure that records from the two tables are not duplicated is option A. This command uses theUNIONclause to combine the records from the legacy table and the newer table into a single result set. TheUNIONclause also eliminates any duplicate records that may exist in both tables, and sorts the result by default. The other options either do not produce the desired result or have syntax errors. For example, option B would join the records from the two tables based on a common column, but not remove any duplicates; option C would return only the records that are common to both tables, but not the ones that are unique to each table; option D would produce a Cartesian product of the records from the two tables, which would increase the number of duplicates.Reference:CompTIA DataSys+ Course Outline, Domain 1.0 Database Fundamentals, Objective 1.2 Given a scenario, execute database tasks using scripting and programming languages.

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20 comments · newest first

Clement 1 month ago

Definitely, we want to avoid duplicates, so UNION is the way to go!

Gerald 1 month ago

I agree, UNION is straightforward for this migration task.

Gail 2 months ago

CROSS JOIN? No way, that creates too many records!

Rhea 2 months ago

INTERSECT is interesting, but it only shows common records, not what we need.

Cheryl 2 months ago

Yeah, but JOIN could also work if we need related data.

Nickolas 2 months ago

I think UNION is the best choice. It combines results without duplicates.

Jaime 2 months ago

Not sure if UNION is enough to avoid duplicates...

Serina 2 months ago

Wait, why not just use IINTERSECT? Seems safer!

Rozella 3 months ago

B) JOIN could work too, right?

Vallie 3 months ago

I think A) UNION makes sense, but what about duplicates?

Sena 3 months ago

A) UNION is the way to go!

Rodrigo 3 months ago

I thought INTERSECT would handle duplicates better.

Alline 3 months ago

Wait, is UNION really the best choice?

Erinn 4 months ago

Definitely A) UNION, no duplicates that way!

Bernardine 5 months ago

I think JOIN might work too, but not for this.

Iraida 5 months ago

A) UNION is the way to go!

Oliva 6 months ago

CROSS JOIN definitely doesn't seem right for this scenario; I think it just combines all records without any filtering.

Lawanda 6 months ago

I feel like INTERSECT could be relevant, but it seems more about finding common records rather than preventing duplicates.

Whitley 6 months ago

I remember practicing with JOINs, but I don't think that's the right choice here since we want to avoid duplicates.

Coleen 6 months ago

I think we might need to use UNION, but I'm not entirely sure if it handles duplicates the way we want.

CompTIA DS0-001 Exam - Topic 1 Question 53 Discussion