该关系模式可能存在哪些函数依赖？验证给定FD是否适用

First, let’s start with the core business rules we have—these are the foundation for figuring out valid functional dependencies (FDs):

• Every doctor has a unique registration number (doc-rego), which maps to their first name, surname, gender, and qualification details.
• Patients are uniquely identified by pat-ID, which ties to their given name, surname, gender, date of birth, address, and phone number.
• Each appointment between a patient and doctor gets a unique app-ID, which specifies the appointment’s date/time and type (long or short).

All Valid Functional Dependencies for ABC #

Based on those rules, here are all the FDs that apply to the relation:

• doc-rego → doc-firstname, doc-surname, doc-gender, doc-qualification
  Since doc-rego is a unique identifier for doctors, knowing this value lets you determine every attribute related to that doctor.
• pat-ID → pat-givename, pat-surname, pat-gender, pat-DOB, pat-addr, pat-phone
pat-ID is the unique patient identifier, so it determines all patient-specific information.
• app-ID → pat-ID, doc-rego, app-datetime, app-type
  Each app-ID is one-of-a-kind per appointment, so it links to exactly one patient, one doctor, and the appointment’s datetime/type.

Verification of the Provided FDs #

Let’s go through each of the FDs you shared to confirm if they hold:

fd1: doc-rego → doc-firstname, doc-surname #

✅ This is valid. Since doc-rego uniquely identifies a doctor, each registration number will always map to the same first name and surname. Note: This FD is incomplete—doc-rego also determines doc-gender and doc-qualification per the given rules—but the stated FD itself is still correct.

fd2: patID → pat-givename, pat-surname, pat-gender, pat-DOB, pat-addr, pat-phone #

✅ This is valid (assuming a typo). The relation uses pat-ID (with a hyphen) as the patient’s unique ID. If patID is just a typo for pat-ID, then this FD holds because the patient ID determines all their personal details.

fd3: app-ID → app-datetime, app-type #

✅ This is valid. Each app-ID is unique to an appointment, so it will always correspond to exactly one date/time and type. Additionally, app-ID should also determine pat-ID and doc-rego because every appointment is between one patient and one doctor.

内容的提问来源于stack exchange，提问作者user24529