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many-many, many-one, and one-one erd relationship in sql tables? PLEASE USE SIMPLE CROWS FOOT ERDS!!!

many-many, many-one, and one-one erd relationship in sql tables? PLEASE USE SIMPLE CROWS FOOT ERDS!!!

Oracle 12c: SQL
Oracle 12c: SQL
3rd Edition
ISBN:9781305251038
Author:Joan Casteel
Publisher:Joan Casteel
Chapter13: Views
Section: Chapter Questions
Problem 2MC
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Does anyone know how to type up a many-many, many-one, and one-one erd relationship in sql tables? PLEASE USE SIMPLE CROWS FOOT ERDS!!!! Also, in the screenshot provided below, my teacher says "FOREIGN KEY (e_ssn) REFERENCES employee (ssn)" at the bottom, what does that mean? If youre having trouble understanding the 1st part of my question, use 2nd shot for reference.

Weak Entity Primary Key So the SQL might be (I'm omitting named constraints due to insufficient space) CREATE TABLE dependent ( d name VARCHAR (90) e ssn CHAR (11) NOT NULL ,gender CHAR (1) ,birth date DATE - I I'm changing this ,relationship VARCHAR (20) , CHECK (gender IN ('M', 'F', 'N', 'T', 'I', 'P')) PRIMARY KEY (d_name, e_ssn) FOREIGN KEY (e_ssn) REFERENCES employee (ssn) A to th the r Note that we don't need to verify the ssn format since it's a FOREIGN KEY and so must have passed the CHECK in employee. The FOREIGN KEY is in place to implement the many-one, and quired Let's explore this. require 3 SSN F_name M_init L_Name Address Salary Sex Employee DDD-DD-DDDD String Character Dependent_of Name Sex Birth_date Relationship Dependent String M/F Date String String String Money M/F
Transcribed Image Text:Weak Entity Primary Key So the SQL might be (I'm omitting named constraints due to insufficient space) CREATE TABLE dependent ( d name VARCHAR (90) e ssn CHAR (11) NOT NULL ,gender CHAR (1) ,birth date DATE - I I'm changing this ,relationship VARCHAR (20) , CHECK (gender IN ('M', 'F', 'N', 'T', 'I', 'P')) PRIMARY KEY (d_name, e_ssn) FOREIGN KEY (e_ssn) REFERENCES employee (ssn) A to th the r Note that we don't need to verify the ssn format since it's a FOREIGN KEY and so must have passed the CHECK in employee. The FOREIGN KEY is in place to implement the many-one, and quired Let's explore this. require 3 SSN F_name M_init L_Name Address Salary Sex Employee DDD-DD-DDDD String Character Dependent_of Name Sex Birth_date Relationship Dependent String M/F Date String String String Money M/F
A one-one example The table would look like this: CREATE TABLE person ); person id INT IDENTITY PRIMARY KEY, person_name VARCHAR (100), license INT, CONSTRAINT pr_license_uq UNIQUE (license), CONSTRAINT pr license f1 FOREIGN KEY REFERENCES driver license (license id)); Person Person id Integer Person_name String Driver license Integer String Expiration_date Date HO-License_of-OH License_id State
Transcribed Image Text:A one-one example The table would look like this: CREATE TABLE person ); person id INT IDENTITY PRIMARY KEY, person_name VARCHAR (100), license INT, CONSTRAINT pr_license_uq UNIQUE (license), CONSTRAINT pr license f1 FOREIGN KEY REFERENCES driver license (license id)); Person Person id Integer Person_name String Driver license Integer String Expiration_date Date HO-License_of-OH License_id State
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