Answered: DBMS 130 Worksheet: JOINS and SET…

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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DBMS 130 Worksheet: JOINS and SET Operations
1
Topic 1: The 5 Joins
Run each of the following statements in APEX.
What are the differences in the results of these SQL statements?
Why are the results different?
SELECT
E.Last_Name
,J.Job_Title
FROM HOL_EMPLOYEES E
INNER JOIN HOL_JOBS J ON E.Job_ID=J.Job_ID;
SELECT
E.Last_Name
,J.Job_Title
FROM HOL_EMPLOYEES E
LEFT OUTER JOIN HOL_JOBS J ON E.Job_ID=J.Job_ID;
SELECT
E.Last_Name
,J.Job_Title
FROM HOL_EMPLOYEES E
RIGHT OUTER JOIN HOL_JOBS J ON E.Job_ID=J.Job_ID;
SELECT
E.Last_Name
,J.Job_Title
FROM HOL_EMPLOYEES E
FULL OUTER JOIN HOL_JOBS J ON E.Job_ID=J.Job_ID;
SELECT
E.Last_Name
,J.Job_Title
FROM HOL_EMPLOYEES E
CROSS JOIN HOL_JOBS J;

DBMS 130 Worksheet: JOINS and SET Operations
2
Topic 2: Write an SQL cartesian product between Regions and Countries.
Copy your APEX here.
How many rows are in the result set?
How could you have calculated the number of rows in the result set BEFORE running your
query?
Topic 3: Briefly explain how set operators handle NULL values.
Run the following 3 SQL queries in APEX which use set operators over these columns.
book_description (hol_books)
book_category_description (hol_book_category)
Most (or all) of the values in these columns are NULL.
How do each of these three set operators handle NULL?
SELECT Book_Description FROM HOL_BOOKS
UNION
SELECT Book_Category_Description FROM HOL_BOOK_CATEGORY
;
SELECT Book_Description FROM HOL_BOOKS
INTERSECT
SELECT Book_Category_Description FROM HOL_BOOK_CATEGORY
;
SELECT Book_Description FROM HOL_BOOKS
MINUS
SELECT Book_Category_Description FROM HOL_BOOK_CATEGORY

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