A) What do you know about the key of SAMPLE? B) Is the relationship between SAMP

Question

A) What do you know about the key of SAMPLE?

B) Is the relationship between SAMPLE and QA TEST an identifying or nonidentifying relationship?

I know SAMPLE is a a weak entity and I know that that means its key comes from either QA TEST or SHIPMENT, but I don't know how to tell which one it comes from (or both). Without knowing that answer, I don't know how I can tell if the relationship is identifying or non-identfying.

Shipment ShipmentID (Primary Key) Shipped Product Product Product Number (Primary Key) QA Test QA Test ID (Primary Key) Product Test Sample

Explanation / Answer

A) As per given relational schema SAMPLE is a a weak entity and its a key which completely depends on SHIPMENT,why because there exists many relationship from SAMPLE side. So that its dependent on SHIPMENT. Even there exists relationship between SAMPLE and QA Test, SAMPLE is a child entity of SHIPMENT only.

B) And coming to the relationship, it is identifying relationship. Because the existence of a row in a SAMPLE table depends on a row in a Shipment table. SO that it is identifying relationship.

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