Oracle_ch9.pptx

8/10/2019 Oracle_ch9.pptx

1/49


2/49

Dr. Chen, Oracle Database System (Oracle) 2

Chapter 9

Joining Data from MultipleTables

(p.284-296; p.312-330)

Jason C. H. Chen,Ph.D.

Professor of MIS

School of Business

Gonzaga University

Spokane, WA 99258 USA

[email protected]


3/49


Objectives

Identify a Cartesian join Create an equality join using the WHERE clause

Create an equality join using the JOIN keyword

Create a non-equality join using the WHEREclause

Create a non-equality join using the JOINON

approach


4/49


Objectives (continued)

Create a self-join using the WHERE clause Create a self-join using the JOIN keyword

Distinguish an inner join from an outer join

Create an outer join using the WHERE clause

Create an outer join using the OUTERkeyword

Use set operators to combine the results of

multiple queries


5/49


Creating additional Tables for chapter 9

Run the following command for creatingadditional tables:

SQL>start c:\oradata\chapter9\JLDB_Build_9.sql

The following four tables will be added toyour database:

Warehouses,

Publisher2, Publisher3 andEmployees


6/49


wh_id location

NUMBER(2) VARCHAR2(12)

ID Name Contact Phone

NUMBER(2) VARCHAR2(23) VARCHAR2(15) VARCHAR2(12)

ID Name Contact Phone

NUMBER(2) VARCHAR2(23) VARCHAR2(15) VARCHAR2(12)

EMPNO LNAME FNAME JOB HIREDATE DEPTNO MTHSAL MGR

NUMBER(4) VARCHAR2(20) VARCHAR2(15) VARCHAR2(19) DATE NUMBER(2) NUMBER(7,2) NUMBER(4)

pk

pk

pk

pk

warehouses

Publishe2

Publishe3

Employees

Publishe2Publishe3

warehouses

Additional Database for chapter 9


7/49


Purpose of Joins

Joins are used to link tables and reconstructdata in a relational database

Joins can be created through:

Conditions in a WHERE clauseUse of JOIN keywords in FROM clause


8/49


How many records will be in the Cartesian Join?

Figure 9-1 Results of a Cartesian Product


9/49


Cartesian Joins

Created by omitting joining condition in the

WHERE clause or through CROSS JOIN

keywords in the FROM clause

Results in every possible row combination

(m * n)

They are useful when

performing certain statistical procedures for

data analysis


10/49


Cartesian Join Example:

Omitted Condition

Figure 9-3 Producing an unintentional Cartesian join

Q: Why

unintentionalCartesian join is

produced?

A: Because Oracle

didnt know whatdata the two tables

had in common.

Q: How to solve

the problem?

A: Use ofEquality Joins (or

inner/simple/natu

ral).

-- chapter 9, Figure 9-3; p.288

SELECT title, nameFROM books, publisher;

(70 rows produced)


11/49


Cartesian Join Example:

CROSS (Cartesian) JOIN Keywords

Figure 9-4 Using the CROSS JOIN keywords


SELECT isbn, title, location, ' ' Count

FROM books, warehouses

ORDER BY location, title;


SELECT isbn, title, location, ' ' Count

FROM books CROSS JOIN warehouses

ORDER BY location, title;

(42 rows produced)


12/49


Equality Joins

Link rows through equivalent data thatexists in both tables

Created by:

Creating equivalency condition in the WHEREclause

Using NATURAL JOIN, JOINUSING, or

JOINON keywords in the FROM clause


13/49


Joining Multiple Tables

Join: combine data from multiple database tablesusing foreign keyreferences

SELECTfield1, field2, ...

FROMtable1, table2

WHEREtable1.joinfield = table2.joinfieldANDsearch_condition(s);

If tables share field names, must prefix field in selectwith table name (table1.field1, table2.field1)

Join condition: part of where clause indicating howtables are related (table1.foreign_key=table2.primary key)

Search conditions can be added to join condition using

AND operator


14/49


Inner Join (cont.)

-- Exatra example

SELECT s_id, s_last, s_first,student.f_id, f_last

FROM student, faculty

WHERE student.f_id =

faculty.f_id;

S_ID S_LAST S_FIRST F_ID F_LAST

------ -------- -------- ---- --------

1 Jones Tammy 1 Cox

2 Perez Jorge 1 Cox

3 Marsh John 1 Cox

4 Smith Mike 2 Blanchard

5 Johnson Lisa 4 Sheng

6 Nguyen Ni 3 Williams

6 rows selected.

Q: whyBrown is not

on the result?

Q: How many rowswill be produced if

C-Join is used?


15/49


Natural JoinInner Join

It can be used when the tables have a singlecommonly named and defined column.

-- Extra Example

SELECT s_id, s_last, s_first,student.f_id, f_last

FROM student, faculty

WHERE student.f_id =

faculty.f_id;

-- Use NATURAL JOIN

SELECT s_id, s_last, s_first, f_id, f_last

FROM student NATURAL JOIN faculty;

S_ID S_LAST S_FIRST F_ID F_LAST

------ -------- -------- ---- --------1 Jones Tammy 1 Cox

2 Perez Jorge 1 Cox

3 Marsh John 1 Cox

4 Smith Mike 2 Blanchard

5 Johnson Lisa 4 Sheng

6 Nguyen Ni 3 Williams

6 rows selected.


16/49


Equality Joins (Traditional Method):

WHERE Clause Example

Figure 9-6 An equality join


17/49


Qualifying Column Names

Columns in

both tables

must be

qualified

Figure 9-7 A column ambiguously defined error

Which table is

pubid from? Is it from

publisheror

books?

-- chapter 9, Figure 9-7(b); p.292

SELECT title, books.pubid,

name

FROM books, publisher

WHERE books.pubid =

publisher.pubid;


18/49


WHERE Clause Supports Join and Other Conditions

Figure 9-8 Including search and join conditions in a WHERE clause

-- Use aliases

-- chapter 9, Figure 9-9; p.294SELECT b.title, b.pubid, p.name

FROM books b, publisher p

WHERE b.pubid = p.pubid

AND (b.cost < 15 OR p.pubid = 1)

ORDER BY title;


19/49


Using a Query Design Diagram

Helpful for creating complicated queries

Can use a formula to derive actual query from diagram

Customerscustomer# (j)

lastname (d)

firstname (d)

Ordersorder# (j)

customer# (j)

Orderitemsorder# (j)

isbn (j)

Query: Display customers lastname, firstname and

books title they purchased

Booksisbn (j)

title (d)

j: join

s: search

d: display


20/49




j: join

s: search

d: display


lastname (d)

firstname (d)

Ordersorder# (j)

customer# (j)


isbn (j)

Booksisbn (j)

title (d)

You can derive your query from the diagram by following these

steps:

1. Place the display fields in the SELECT clause

2. List all of the tables in the FROM clause3. Include the links in join conditions in the WHERE clause

4. Include all of the search fields in the WHERE clause (if needed)

Figure: Join query design diagram


21/49




j: join

s: search

d: display


lastname (d)

firstname (d)

Ordersorder# (j)

customer# (j)


isbn (j)

Booksisbn (j)

title (d)



SELECTc.lastname, c.firstname, b.title

FROMcustomers c, orders o, orderitems oi, books b

WHEREc.customer# = o.customer#ANDo.order# = oi.order#

ANDoi.isbn = b.isbn

ORDER BY lastname, firstname;


22/49


Joining More Than Two Tables

Figure 9-10 Joining four tables

Joining

four tables

requiresthree join

conditions

Joining N

tablesrequires

___ join

conditions


23/49



books title and only in COMPUTER category

j: join

s: search

d: display


lastname (d)

firstname (d)

Ordersorder# (j)

customer# (j)


isbn (j)

Booksisbn (j)

title (d)

_______



SELECTc.lastname, c.firstname, b.title

FROMcustomers c, orders o, orderitems oi, books b

WHEREc.customer# = o.customer#ANDo.order# = oi.order#

ANDoi.isbn = b.isbn

ORDER BY lastname, firstname;

ANDcategory = COMPUTER

category (s)


24/49


25/49


No Qualifiers with a NATURAL JOIN

Figure 9-13 Column qualifier error with a NATURAL JOIN

Natural Join keyword (e.g, pubid), we are not required to be specified

when the two tables have it in common.

Therefore most developers avoid using a NATURAL JOIN because it

can cause unexpected results.


26/49


Equality Joins: JOINUSING

Figure 9-14

Performing

a join with

the JOIN

USING

keywords


27/49


Break

Assignments (#2 & #5 on p. 329; see at the end of

the slides)

Figure out how to produce the output with $

displayed (below is a sample output for #5, p.329)

hint: a) column

b) TO_CHAR (see p.365-367 and learning to learn)TITLE PROFIT

------------------------------ --------

PAINLESS CHILD-REARING $37.45

HOW TO MANAGE THE MANAGER $16.55

PAINLESS CHILD-REARING $37.45

TO_CHAR( )PROFIT,_______


28/49


Query: list all author IDs with books in the Children category

Query: list all author IDs with books in the Family Life category

SELECT ba.authorid

FROM books b JOIN bookauthor baUSING (isbn)

WHERE category = 'FAMILY LIFE;

SELECT ba.authorid

FROM books b JOIN bookauthor baUSING (isbn)

WHERE category = 'CHILDREN';


29/49


Query: list all author IDs with books in the Family Life or

Children category

-- chapter 9, Figure 9-28; p. 313(version 2)SELECT ba.authorid

FROM books b JOIN bookauthor ba

USING (isbn)

WHERE category = FAMILY LIFE

Anything notappropriate in

the output?

ORcategory = CHILDREN;

How to take care this type of

problem in an easy way?


30/49


Using Set Operators to Combine Query

Results

Performs set operations on outputs of twounrelated queries

They all require that both queries

have the same number of display fields in the

SELECT statement, and that

each field in the first query has the same datatype as the corresponding column in the secondquery.


31/49


A B

SET THEORY


32/49


C

SET THEORY

=A-B

=B-A

=A INTERSECTB

All Regions =A UNIONB

(with Ccounted just once)

A-B B-A


33/49


C

SET THEORY

A MINUS B=D

B MINUS A=E

A INTERSECTB=

A UNIONB =

D E

A UNION ALLB = D+C+E+__C

C

D+C+E

A

B


34/49


Oracle 11g/SQL SetOperator (Table 9-2)

UNION (see Figure 9-28)

returns all rows from both queries, but ONLY displaysduplicate rows once

UNION ALL (see Figure 9-30) returns all (duplicate)rows from both queries, and displays

ALL duplicate rows

INTERSECT (see Figure 9-34) returns all matching rows that are returned by both queries

MINUS (see Figure 9-35) returns all rows returned by the first query minus the

matching rows returned by the second query

Use to select data from multiple tables not connected

with foreign key relationshipsUsed to combine the results of two or more SELECT

statements


35/49


Query: list all author IDs with books in the Family Life or

Children category

SELECT ba.authoridFROM books b JOIN bookauthor ba

USING (isbn)

WHERE category = 'FAMILY LIFE

SELECT ba.authorid

FROM books b JOIN bookauthor ba

USING (isbn)

WHERE category = 'CHILDREN';

UNION

Figure 9-28 Producing an unduplicated combined list

with the UNION set operator


36/49


Set Operators: UNION and UNION ALL Examples

What is the difference on the outputs?

Q li t ll t b d th t h h


37/49


Figure 9-34 Identifying

overlapping values with theINTERSECT set operator

Query: list all customer numbers and those customers who have

placed an order recently

SELECT customer#FROM customers

SELECT customer#FROM orders;

INTERSECT


38/49


Query: list all customer numbers but

haventplaced an order recently

Figure 9-35 Subtract result sets

with the MINUS set operator

SELECT customer#FROM customers

SELECT customer#FROM orders;

MINUS


39/49


Query:A list of faculty members whose offices are in the BUS

building. (Extra example)

FACULTY

f_first (d)f_last (d)

loc_id (j)

LOCATION

loc_id (j)

bldg_code (s)

SELECT f_first, f_last

FROM faculty, location

WHERE faculty.loc_id = location.loc_id

AND bldg_code = 'BUS';

MORE EXAMPLES on SET OPERATORS

You need to run the following command

to make the example work:

@ c:\oradata\NW_CW\northwoods.sql


40/49


Query:A list of faculty members who have taught a course in theBUS building.

FACULTY

f_first (d)

f_last (d)f_id (j)

LOCATION

loc_id (j)

bldg_code (s)

COURSE_

SECTION

f_id (j)loc_id (j)

SELECT DISTINCT f_first, f_last

FROM faculty, location, course_section

WHERE faculty.f_id = course_section.f_id

AND location.loc_id = course_section.loc_id



41/49



building orwho have taught a course in the BUS building. (extra

example)




AND bldg_code = 'BUS'

SELECT f_first, f_lastFROM faculty, location, course_section




UNION

Officein BUS

Taught

courses

in BUS


42/49



building andwho have taught a course in the BUS building.

(extra example)





SELECT f_first, f_lastFROM faculty, location, course_section




INTERSECT

Officein BUS

Taught

courses

in BUS

A d NEXT


43/49


And NEXT ...

Query:A list of faculty members who have taught a course in the

BUS building, but whose office are NOTlocated in the BUS


FROM faculty, location, course_section








MINUS

Office

in BUS

Taught

coursesin BUS


44/49


Practice all the examples in the text. A Script file is available on the Bb (file

name: ch9Queries.sql)

After completing all examples, do the HW.

H k H d O A i t


45/49


Homework - Hands-On Assignments

Read and Practice all examples on Chapters 9

1. Run the script files (in the folder \oradata\chapter9\):

JLDB_Build_9.sql 2a. Read Oracle assignment and create a script file

Oracle_ch9_Lname_Fname.sql for questions (#2 & #5 ; p.329)on Hands-on Assignments (use TWO SQL queries, traditionalone and with JOIN read instructions carefully)

2b. Be sure to use i) traditional method, ii) JOIN keyword, iii) draw

Query Design Diagrams for each problem, and iv) use COLUMNstatement to produce readable outputssee next slide for details

3. Execute and test one problem at a time and make sure they are allrunning successfully.

4. When you done, spool the script files (see next slide for spoolinginstructions) and email the file

5. Include Query Design Diagrams

Email me with one attachment

(Oracle_ch9_Spool_Lname_Fname.) to:

[email protected] subject title of

bmis441_Oracle_ch9

How to Spool your Script and Output Files and


46/49



add Query Design Diagrams

After you tested the script file of Oracle_ch9_Lname_Fname.sql successfully,

follow the instructions below to spool both script and output files:Step 0. Run the following script file from SQL*Plus (since you have created

JLDB tables)

Start c:\oradata\chapter9\JLDB_Build_9.sql

1. type the following on SQL>

Spool c:\oradata\Oracle_ch9_Spool_Lname_Fname.txt(make sureyour name is entered)

2. open Oracle_ch9_Lname_Fname.sql that you already tested

3. copy and paste all the SQL commands (including all comments) to theSQL*PLUS

4. type Spool Off on the SQL>The output should contain your personal information, all SQL commands and

their solution on the .txt file and saved in C: drive (oradata\folder).

Be sure that COLUMNcommands might be needed on the script file to alignthe output.


47/49



add Query Design Diagrams (continued)

5. Next, you should use MS/Word to open the *.txt file andinclude/DRAWQuery Design Diagram figures for queries withmultiple tables. You may use font of Courier new to align theoutput.

6. Save it as *.doc (or docx) file.

Email me with the *.doc (or *.docx) file that includes all required documents

with attachment to:

[email protected] subject title of

bmis441_Oracle_ch9


48/49


Summary

Data stored in multiple tables regarding a single

entity can be linked together through the use ofjoins

A Cartesian join between two tables returns everypossible combination of rows from the tables; the

resulting number of rows is always m * n

An equality join is created when the data joiningthe records from two different tables are an exactmatch

A non-equality join establishes a relationship basedupon anything other than an equal condition

Self-joins are used when a table must be joined to

itself to retrieve needed data


49/49

Summary (continued)

Inner joins are categorized as being equality, non-equality, or self-joins

An outer join is created when records need to beincluded in the results without havingcorresponding records in the join tables

The record is matched with a NULL record so it will beincluded in the output

Set operators such as UNION, UNION ALL,INTERSECT, and MINUS can be used tocombine the results of multiple queries

Oracle_ch9.pptx

Documents

Transcript of Oracle_ch9.pptx