PostgreSQL PGCES-02 Exam - Topic 9 Question 25 Discussion

Actual exam question for PostgreSQL's PGCES-02 exam

Question #: 25
Topic #: 9

A table is defined as below. Select the most suitable description about the foreign key constraint. CREATE TABLE master (id INTEGER PRIMARY KEY, name TEXT); CREATE TABLE record (id INTEGER REFERENCES master (id), count INTEGER);

AIf any row exists in the 'record' table, no change can be made to the 'master' table.

BIf the 'record' table contains a row with an 'id', no change can be made at all to the corresponding 'id' row in the 'master' table.

CIf the 'record' table contains a row with an 'id', the corresponding 'id' row in the 'master' table cannot be deleted.

DThe 'record' table cannot have duplicate 'id's.

EThese SQL statements are invalid; no constraints are created.

Show Suggested Answer

Suggested Answer: A

by Veronika at May 07, 2022, 02:41 AM

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Mendy

4 months ago

B is too strict; you can still update master if record has an id.

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Dan

4 months ago

Wait, are these SQL statements really valid? Seems off to me.

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Rikki

5 months ago

D is not true, record can have duplicates unless specified otherwise.

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Jolene

5 months ago

I disagree, A is misleading. Changes can still be made to master.

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Mabel

5 months ago

C is correct! You can't delete from master if record has that id.

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Irving

5 months ago

I feel like option D is about uniqueness in the 'record' table, but I don't think that's what the foreign key constraint is about. I might be confused on this one!

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Leonida

5 months ago

I'm not entirely sure, but I remember something about foreign keys preventing changes to the parent table if there are dependent rows. Could that relate to option A or C?

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Daren

5 months ago

I think the foreign key constraint means that if there's a related row in the 'record' table, you can't delete the corresponding row in 'master'. So maybe it's option C?

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Micah

5 months ago

I practiced a similar question, and I think the foreign key allows for updates in 'master' as long as there are no dependent rows in 'record'. So, I might lean towards option C.

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Tawna

5 months ago

This is a good example of the kind of question I need to watch out for. It seems simple, but you have to really think about the privacy and security requirements. I'm going to mark this one as False.

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Marylyn

5 months ago

This seems simple enough. I'll just follow the instructions and double-check my work before submitting.

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Amber

5 months ago

This question seems a bit tricky. I'll need to carefully consider the differences between the production and non-production environments to determine the license cost.

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Domonique

5 months ago

"External area" doesn't seem right at all, but I'm confused between "Multiple areas" and the others. It's been a while since we reviewed these concepts!

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Valda

11 months ago

I'm just impressed they managed to fit all this into a single exam question. That's some serious database compression right there!

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Royal

9 months ago

D) The 'record' table cannot have duplicate 'id's.

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Domonique

9 months ago

C) If the 'record' table contains a row with an 'id', the corresponding 'id' row in the 'master' table cannot be deleted.

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Ty

9 months ago

B) If the 'record' table contains a row with an 'id', no change can be made at all to the corresponding 'id' row in the 'master' table.

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Carri

9 months ago

C) If the 'record' table contains a row with an 'id', the corresponding 'id' row in the 'master' table cannot be deleted.

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Leah

9 months ago

B) If the 'record' table contains a row with an 'id', no change can be made at all to the corresponding 'id' row in the 'master' table.

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Julie

10 months ago

A) If any row exists in the 'record' table, no change can be made to the 'master' table.

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Karma

10 months ago

A) If any row exists in the 'record' table, no change can be made to the 'master' table.

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Cammy

10 months ago

Exactly, it's a way to link the two tables together and prevent any inconsistencies.

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Tanesha

10 months ago

So, basically, the foreign key constraint ensures that you can't delete a record in the 'master' table if it's being referenced in the 'record' table.

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Latonia

10 months ago

I agree, that sounds right. It's all about maintaining data integrity.

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Fanny

10 months ago

I think the answer is C) If the 'record' table contains a row with an 'id', the corresponding 'id' row in the 'master' table cannot be deleted.

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Verdell

11 months ago

Option E? Really? These are perfectly valid SQL statements. Someone needs to brush up on their database knowledge.

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Avery

11 months ago

Haha, good thing the 'record' table doesn't have a column called 'count_of_beers'. That would be a whole different kind of foreign key constraint!

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Dominic

10 months ago

C) If the 'record' table contains a row with an 'id', the corresponding 'id' row in the 'master' table cannot be deleted.

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Nickole

10 months ago

A) If any row exists in the 'record' table, no change can be made to the 'master' table.

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Dion

11 months ago

I agree with Stephane. This is a classic example of a foreign key constraint, which prevents orphaned records in the dependent table.

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Stephane

11 months ago

Option C is the correct answer. The foreign key constraint ensures that the corresponding row in the master table cannot be deleted if there is a reference to it in the record table.

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