Chapter 2
Connecting to Oracle 12c
and
Basic SQL SELECT Statements
Jason C.H. Chen, Ph.D.
Professor of MIS
School of Business, Gonzaga University
Spokane, WA 99258 USA
chen@jepson.gonzaga.edu
Dr. Chen, Business Database Systems (Oracle)
Objectives
• Learn how to connect to Oracle 12c (client/server and
Personal)
• Create the initial database
• Learn database objects and SQL commands and components
• Identify keywords, mandatory clauses, and optional clauses in
a SELECT statement
• Select and view one/all columns of a table
• Display multiple columns of a table
• Use a column alias to clarify the contents of a particular
column
• Perform basic arithmetic operations in the SELECT clause
• Remove duplicate lists using either the DISTINCT or
UNIQUE keyword
• Use concatenation to combine fields, literals, and other data
Dr. Chen, Business Database Systems (Oracle)
2
Connect to Oracle 12c
• There are two ways connecting to and working
with Oracle 12c
• SQL Plus
– a command driven facility
• SQL Developer
– a GUI facility
Indicate the following link to include java.exe (use “Browse”):
c:\program Files(x86)\java\jdk1.7.0…\bin\java.exe
(choose the most recent version, may not be jdk1.7.0…)
Dr. Chen, Business Database Systems (Oracle)
3
YOUR TURN
How to Access Your Oracle12c Account
• User Name: <C##your lastname>
• Password: <…> <BMIS441> [case sensitive]
Dr. Chen, Business Database Systems (Oracle)
4
Connect to Oracle 12 using
SQL Plus
• User Name: <C##your lastname>
• Password: <…> <BMIS441> [case sensitive]
type “exit”
to quit the
system
Dr. Chen, Business Database Systems (Oracle)
Figure 2-1 SQL*Plus Interface
Connect to Oracle 12c using
SQL Developer for the first time
If asked if you like to
migrate settings, You
click on “No”
Dr. Chen, Business Database Systems (Oracle)
Connect to Oracle 12c using
SQL Developer for the first time
Sometimes you need to do the following …
(also available on the Installation Guide on Bb)
Now run SQL Developer. You will be prompted to enter
the pathname for your newly installed Java JDK program.
If the program was installed in C and you run a 64-bit
version of Windows, the destination will be as follows:
C:\Program Files (x86)\Java\jdk1.8.0…\bin\java.exe. If
not, you click Browse and find the Java program yourself,
just make sure you point to the JDK version not the JRE.
Dr. Chen, Business Database Systems (Oracle)
YOUR TURN
How to Access Your Oracle12c Account
• User Name: <C##your lastname>
• Password: <…> <BMIS441> [case sensitive]
SBORA12
Dr. Chen, Business Database Systems (Oracle)
8
Complete the information on the Database Connection Screen
Create a new connection
click on
Dr. Chen, Business Database Systems (Oracle)
Complete the information on the Database Connection Screen
Click on “Basic” and select “TNS”
Dr. Chen, Business Database Systems (Oracle)
Complete the information on the Database Connection Screen
Dr. Chen, Business Database Systems (Oracle)
Complete the information on the Database Connection Screen
#1
#2
SBAORA12
#3
Dr. Chen, Business Database Systems (Oracle)
Complete the information on the Database Connection Screen
Dr. Chen, Business Database Systems (Oracle)
Connect to Oracle 12c using
SQL Developer
Dr. Chen, Business Database Systems (Oracle)
Figure 2-2 SQL Developer Interface
Connect to Oracle 11g using
Personal SQL Developer
click on TNS
(password is created during the Oracle installation)
Dr. Chen, Business Database Systems (Oracle)
Click on “+” (Expand), the Connection Box is prompted
(other information are no longer needed)
Dr. Chen, Business Database Systems (Oracle)
Click , if “output screen”
not displayed
Dr. Chen, Business Database Systems (Oracle)
An output screen from a SQL command:
SELECT * FROM customers;
Dr. Chen, Business Database Systems (Oracle)
Oracle Download
Dr. Chen, Business Database Systems (Oracle)
Database Objects and Queries
• An Oracle database consists of multiple user accounts
• Each user account owns database objects
•
•
– Tables
– Views
– Stored programs, etc.
Query: command to perform operation on database
object
Structured Query Language (SQL)
– Industry standard query language for most of relational
databases
– Consists of about 30 commands
Dr. Chen, Business Database Systems (Oracle)
20
Basic SQL Concepts and Commands
SQL (Structured Query Language) is used to
manipulate the database.
There are two basic types of SQL commands:
Data Definition Language (DDL)
Data Manipulation Language (DML)
DDL commands work with the structure of the objects
(tables, indexes, views) in the database.
DML commands work with the data in the database
(i.e.,manipulate the data).
Reserved words - SQL command words
Dr. Chen, Business Database Systems (Oracle)
SQL Components
ORACLE
(SQL Components)
DDL
DML
D.B.
DCL
(Create Table structure
and insert database)
Dr. Chen, Business Database Systems (Oracle)
22
DDL Commands
• Used to create and modify the structure of
database objects
–
–
–
–
–
CREATE
ALTER
DROP
GRANT
REVOKE
• DDL commands execute as soon as they are
issued, and do not need to be explicitly saved
Dr. Chen, Business Database Systems (Oracle)
23
DML Commands
• Used to insert, view, and modify database data
–
–
–
–
INSERT
UPDATE
DELETE
SELECT
• DML commands need to be explicitly saved or
rolled back
– COMMIT
– ROLLBACK
– SAVEPOINT
Dr. Chen, Business Database Systems (Oracle)
24
Create the JustLee Database
• Use the provided script to create the
database so you can follow the chapter
examples
• Verify table contents (structure) using the
DESCRIBE command
Dr. Chen, Business Database Systems (Oracle)
25
Scripts
• Scripts are simply files that contain a sequence of
SQL and/or PL/SQL commands that can be
executed in SQL*Plus.
• Note:
– SQL and PL/SQL(to be introduced) are two
languages Oracle uses.
– SQL*Plus is the tool we use to access Oracle.
– SQL*Plus can execute both SQL and PL/SQL
commands plus it has its own commands.
Dr. Chen, Business Database Systems (Oracle)
26
Class Exercise
• Create a new folder on c:\ as follows:
c:\oradata\chapter2
• Download all files in chapter 2 from Bb (under
“Course Documents”) into c:\oradata\chapter2\
• Logon to SQL*Plus and type the following
command (not on SQL Developer)
SQL> start c:\oradata\chapter2\JLDB_Build.sql
or,
SQL> @ c:\oradata\chapter2\JLDB_Build.sql
SQL> SELECT * FROM publisher;
Dr. Chen, Business Database Systems (Oracle)
27
Class Exercise (continued)
• A table name only can be created once and
saved in the current database. Therefore, if
you re-do the previous start command you
will receive error message.
• To avoid the problem, you need DROP the
tables from the database before those tables
(using the same names) are recreated.
• Type the following command for
SQL> start c:\oradata\chapter2\JLDB_Drop.sql
SQL> SELECT * FROM publisher;
Dr. Chen, Business Database Systems (Oracle)
28
Installing Personal Oracle12c
• I created a “Discussion Questions” on the Bb for you to
share (or post question) your experience on installation of
Oracle 12c. Please participate and it will be also your
part of class performance.
•
• Please note that if your computer with 64-bit operating
system, you need to download 64-bit Oracle 12c from the
Oracle site (www.oracle.com) or type in keyword search
of “Oracle 12c download”.
Dr. Chen, Business Database Systems (Oracle)
29
How to verify “Created” Tables and their Structure?
Figure 2-3 List of existing (created) tables
Figure 2-3 List the structure of the BOOKS table
Also try to type the same commands on SQL>
Dr. Chen, Business Database Systems (Oracle)
SELECT Statement Syntax
• SELECT statements are used to retrieve data from
the database
• A SELECT statement is referred to as a query
• Syntax gives the basic structure, or rules, for a
command
• Optional clauses and keywords are shown in
brackets
Dr. Chen, Business Database Systems (Oracle)
31
SELECT Statement Syntax (continued)
Figure 2-5 Syntax for the SELECT statement
•
•
•
•
SELECT and FROM clauses are required
SELECT clause identifies column(s)
FROM clause identifies table(s)
Each clause begins with a keyword
Dr. Chen, Business Database Systems (Oracle)
Your turn …
• -- chapter 2, Figure 2-6; p. 32
• SELECT * FROM CUSTOMERS;
• -- chapter 2, Figure 2-7; p. 33
• SELECT title FROM books;
•
•
•
•
•
•
-- chapter 2, Figure 2-8; p. 34
SELECT TITLE FROM BOOKS;
SELECT title from books;
SELECT title FROM books;
SELECT TITLE
FROM BOOKS;
Dr. Chen, Business Database Systems (Oracle)
33
Your turn …
•
•
•
•
•
•
•
•
•
•
•
-- chapter 2, Figure 2-9; p. 35
SELECT title, pubdate FROM books;
-- chapter 2, Figure 2-10; p. 36
SELECT pubdate, title FROM books;
-- chapter 2, Figure 2-11; p. 37
SELECT title AS "Title of Book", category
FROM books;
-- chapter 2, Figure 2-12; p. 38
SELECT title, retail price FROM books;
-- chapter 2, Figure 2-13; p. 40
SELECT title, retail-cost profit FROM books;
• -- chapter 2, Figure 2-14; p. 41
• SELECT * FROM books;
Dr. Chen, Business Database Systems (Oracle)
34
Selecting All Data in a Table
• Substitute an asterisk for the column names in a
SELECT clause
Figure 2-6 Command to select all data in a table
Dr. Chen, Business Database Systems (Oracle)
Selecting One Column from a Table
• Enter column name in SELECT clause
-- CASE is not sensitive
-- chapter 2, Figure 2-8; p. 34
SELECT TITLE FROM BOOKS;
SELECT title from books;
SELECT title FROM books;
SELECT TITLE
FROM BOOKS;
Figure 2-7 Command to select in a single column
Dr. Chen, Business Database Systems (Oracle)
Selecting Multiple Columns from a Table
• Separate column names with a comma
-- chapter 2, Figure 2-10; p. 36
SELECT pubdate, title
FROM books;
Figure 2-10 Reversed column sequence in the
SELECT clause
Since the output from
SQL_Developer can’t be saved
(captured) in a file we will learn
how to capture it next.
Figure 2-9 Command to select multiple columns from a table
Dr. Chen, Business Database Systems (Oracle)
Break !
Hands-On Assignments
• In class exercise (p.54)
– #1 and #3, or
• Create and save as an *.sql file, eg.
Oracle_ch2_Chen_Jason.sql
• as Assignment due next class
– Turn in a hardcopy
• Hint:
Select …
--#1
FROM …
SELECT * FROM books;
--#3
SELECT title, pubdate "Publication Date"
FROM books;
Dr. Chen, Business Database Systems (Oracle)
38
Capture (Spool) an output
SQL> Spool c:\oradata\chapter2\Oracle_ch2_Spool_Lname_Fname.txt
SQL> --#3
SQL> SELECT title, pubdate AS "Publication Date"
FROM books;
SQL> Spool off
Then, open Oracle_ch2_Spool_Lname_Fname.txt in the folder
of oradata\chapter2\
Verify the output
See detailed steps on (Bb):
Instruction_on_Creating_sql_and_SPOOL.pptx
Dr. Chen, Business Database Systems (Oracle)
39
The following output is from SQL>
SQL> select * from books;
ISBN
TITLE
PUBDATE
PUBID
COST
---------- ------------------------------ --------- ---------- ---------RETAIL DISCOUNT CATEGORY
---------- ---------- -----------1059831198 BODYBUILD IN 10 MINUTES A DAY 21-JAN-05
30.95
FITNESS
0401140733 REVENGE OF MICKEY
22
FAMILY LIFE
14-DEC-05
1
4
18.75
14.2
4981341710 BUILDING A CAR WITH TOOTHPICKS 18-MAR-06
59.95
3 CHILDREN
2
37.8
8843172113 DATABASE IMPLEMENTATION
55.95
COMPUTER
04-JUN-03
3
31.4
3437212490 COOKING WITH MUSHROOMS
19.95
COOKING
28-FEB-04
4
12.5
3957136468 HOLY GRAIL OF ORACLE
75.95
3.8 COMPUTER
31-DEC-05
3
47.25
Question: How can we improve the output?
(see chapter 2, Figure 2-14(b) on Ch2Queries.sql)
We will learn it later and more in the later chapters.
Dr. Chen, Business Database Systems (Oracle)
The following output is from SQL>
SQL> select * from books;
ISBN
TITLE
PUBDATE
PUBID
COST
---------- ------------------------------ --------- ---------- ---------RETAIL DISCOUNT CATEGORY
---------- ---------- -----------1059831198 BODYBUILD IN 10 MINUTES A DAY 21-JAN-05
30.95
FITNESS
0401140733 REVENGE OF MICKEY
22
FAMILY LIFE
14-DEC-05
1
4
18.75
14.2
4981341710 BUILDING A CAR WITH TOOTHPICKS 18-MAR-06
59.95
3 CHILDREN
2
37.8
8843172113 DATABASE IMPLEMENTATION
55.95
COMPUTER
04-JUN-03
3
31.4
3437212490 COOKING WITH MUSHROOMS
19.95
COOKING
28-FEB-04
4
12.5
3957136468 HOLY GRAIL OF ORACLE
75.95
3.8 COMPUTER
31-DEC-05
3
47.25
Question: How can we produce a readable output format?
Dr. Chen, Business Database Systems (Oracle)
Formatting Output in SQL*Plus
• To change default column headings:
– Specify alternate column headings: SELECT fieldname1
"heading1_text", fieldname2 "heading2_text", ...
– Use an alias for column headings: SELECT fieldname1 AS
alias_name1...
– Use column statement
• To change SQL*Plus line and page size settings
– Select Options/Environment on menu bar
– Modify linesize and pagesize to desired values
• You may also type the following commands at SQL>
– SQL> SET LINESIZE 80
– SQL> SET PAGESIZE 45
• Please download chapter 14 (pdf file on Bb) for more
commands on formatting output.
Dr. Chen, Business Database Systems (Oracle)
42
Advanced SQL Commands
clear screen;
column <fieldname> format a15 wrap
column <fieldname> format a15 word
column <fieldname> format a20 heading ‘description for the field’
column <fieldname> format a15 truncate
column <fieldname> format $999.99
-- note: default is wrap
-- formatting output (try it on the SQL>)
-- chapter 2, Figure 2-14(b); p. 41
clear screen
SET LINESIZE 80
SET PAGESIZE 45
column title format a12 heading 'Book Title' WORD
column PubID format 99 heading 'ID'
column Cost format $999.99
column retail format $999.99
SELECT *
FROM books;
Dr. Chen, Business Database Systems (Oracle)
Read and practice all the
SQL commands in
Ch2Queries.sql file (esp.
those at the end of the file)
Here is a better output after formatting output:
ISBN
Book Title
---------- -----------1059831198 BODYBUILD IN
10 MINUTES
A DAY
0401140733 REVENGE OF M
ICKEY
4981341710 BUILDING A C
AR WITH TOOT
HPICKS
8843172113 DATABASE IMP
LEMENTATION
3437212490 COOKING WITH
MUSHROOMS
3957136468 HOLY GRAIL O
F ORACLE
1915762492 HANDCRANKED
COMPUTERS
9959789321 E-BUSINESS T
HE EASY WAY
2491748320 PAINLESS CHI
LD-REARING
0299282519 THE WOK WAY
TO COOK
8117949391 BIG BEAR AND
LITTLE DOVE
0132149871 HOW TO GET F
ASTER PIZZA
9247381001 HOW TO MANAG
E THE MANAGE
R
ISBN
Book Title
---------- -----------2147428890 SHORTEST POE
MS
PUBDATE
ID
COST
RETAIL
DISCOUNT CATEGORY
--------- --- -------- -------- ---------- -----------21-JAN-05
4
$18.75
$30.95
FITNESS
14-DEC-05
1
$14.20
$22.00
FAMILY LIFE
18-MAR-06
2
$37.80
$59.95
3 CHILDREN
04-JUN-03
3
$31.40
$55.95
COMPUTER
28-FEB-04
4
$12.50
$19.95
COOKING
31-DEC-05
3
$47.25
$75.95
3.8 COMPUTER
21-JAN-05
3
$21.80
$25.00
COMPUTER
01-MAR-06
2
$37.90
$54.50
COMPUTER
17-JUL-04
5
$48.00
$89.95
4.5 FAMILY LIFE
11-SEP-04
4
$19.00
$28.75
COOKING
08-NOV-05
5
$5.32
$8.95
11-NOV-06
4
$17.85
$29.95
09-MAY-03
1
$15.40
$31.95
CHILDREN
1.5 SELF HELP
BUSINESS
PUBDATE
ID
COST
RETAIL
DISCOUNT CATEGORY
--------- --- -------- -------- ---------- -----------01-MAY-05
5
$21.85
$39.95
LITERATURE
14 rows selected.
Dr. Chen, Business Database Systems (Oracle)
Break !
Hands-On Assignments
HW (Odd numbers only (pp.54-55), but do #1 at the end
as it will affect the rest of problems)
- run the following two commands:
Start c:\oradata\chapter2\JLDB_Drop.sql
Start c:\oradata\chapter2\JLDB_Build.sql
Output should be formatted in a very good manner.
Scripting file name: Oracle_ch2_Lname_Fname.sql
Spooled file name: Oracle_ch2_Spool_Lname_Fname.txt
Upload the spooled file (*.txt) to the Bb (under
“Assignments & Projects”) by the deadline.
Dr. Chen, Business Database Systems (Oracle)
Homework - Hands-On Assignments
Upload the spooled file (*.txt) to the Bb (under “Assignments
& Projects”) by the deadline.
Read and Practice all examples on Chapters 2
• 1. Run two script files: JLDB_Drop.sql and
JLDB_Build.sql
• 2. Read Oracle assignment and create a script file
Oracle_ch2_Lname_Fname.sql for odd number
questions on “Hands-on Assignments”. Use
appropriate COLUMN statements to produce readable
outputs
• 3. Execute and test one problem a time (do #1 at the
end, why?) and make sure they are all running
successfully. Include class and personal information.
• 4. When you done, spool the script files (see next slide
for spooling instructions) and upload the spooled file
(Oracle_ch2_Spool_Lname_Fname.txt) to Bb by
midnight this coming Sunday. Turn in a hardcopy to
me in the class.
Dr. Chen, Business Database Systems (Oracle)
How to Spool your Script and Output Files
After you tested the script file of Oracle_ch2_Lname_Fname.sql successfully,
follow the instructions below to spool both script and output files:
Step 0. Run the following two script files from SQL*Plus (since you have
created JLDB tables)
– Start c:\oradata\chapter2\JLDB_Drop.sql
– Start c:\oradata\chapter2\JLDB_Build.sql
• 1. type the following on SQL>
– Spool c:\oradata\chapter2\Oracle_ch2_Spool_Lname_Fname.txt (make sure your name
is entered)
• 2. open Oracle_ch2_Lname_Fname.sql that you already tested
• 3. copy and paste all the SQL commands (including all comments) to the
SQL*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\chapter2\ folder)
Upload the spooled file (*.txt) to the Bb (under “Assignments &
Projects”) by the deadline.
Dr. Chen, Business Database Systems (Oracle)
47
Operations within the SELECT Statement
•
•
•
•
Column alias can be used for column headings
Perform arithmetic operations
Suppress duplicates
Concatenate data
• List the alias after the column heading
• AS keyword is optional
• Enclose in double quotation marks:
– If it contains blank space(s)
– If it contains special symbol(s)
– To retain case
Dr. Chen, Business Database Systems (Oracle)
48
Column Alias Example
Figure 2-11 Using a column alias
Dr. Chen, Business Database Systems (Oracle)
Figure 2-12 Using a column alias without
the AS keyword
49
Using Arithmetic Operations
• Arithmetic operations
–
–
–
–
Executed left to right
Multiplication and division are solved first
Addition and subtraction are solved last
Override order with parentheses
Dr. Chen, Business Database Systems (Oracle)
50
Example Arithmetic Operation with
Column Alias
Figure 2-13 Using a column alias for an arithmetic expression
Dr. Chen, Business Database Systems (Oracle)
51
Figure 2-14 NULL values in the Discount column
Dr. Chen, Business Database Systems (Oracle)
Using DISTINCT and UNIQUE
• Enter DISTINCT or UNIQUE after SELECT keyword to suppress duplicates
-- chapter 2, Figure 2-16; p. 43
-- without DISTINCT
SELECT state
FROM customers;
SQL> SELECT state FROM customers;
ST
-FL
CA
FL
ID
WA
NY
TX
WY
CA
GA
IL
MA
FL
WY
FL
CA
MI
GA
NJ
NJ
20 rows selected.
Dr. Chen, Business Database Systems (Oracle)
Figure 2-16 List of unduplicated states for customers
More example
-- chapter 2, Figure 2-17; p. 44
SELECT DISTINCT state, city
FROM customers;
Figure 2-17 Unduplicated list of cities for customers
Dr. Chen, Business Database Systems (Oracle)
Using Concatenation
• You can combine data
with a string literal
• Use the concatenation
operator, ||
• It allows the use of
column aliases
SELECT firstname, lastname
FROM customers;
Dr. Chen, Business Database Systems (Oracle)
Figure 2-18 Concatenation of two columns
55
Concatenation Examples with Alternate name
Figure 2-219 Using a string literal in concatenation
Dr. Chen, Business Database Systems (Oracle)
Figure 2-20 Using a column alias for concatenated values
56
Break !
Hands-On Assignments
HW (Odd numbers only (pp.54-55), but do #1 at the end
as it will affect the rest of problems)
- run the following two commands:
Start c:\oradata\chapter2\JLDB_Drop.sql
Start c:\oradata\chapter2\JLDB_Build.sql
Output should be formatted in a very good manner.
Scripting file name: Oracle_ch2_Lname_Fname.sql
Spooled file name: Oracle_ch2_Spool_Lname_Fname.txt
Upload the SQL and spooled files (*.sql and *.txt) to the Bb
(under “Assignments & Projects”) by the deadline
Dr. Chen, Business Database Systems (Oracle)
Homework - Hands-On Assignments
Upload the SQL and spooled files (*.sql and *.txt) to the Bb
(under “Assignments & Projects”) by the deadline.
Read and Practice all examples on Chapters 2
• 1. Run two script files: JLDB_Drop.sql and
JLDB_Build.sql
• 2. Read Oracle assignment and create a script file
Oracle_ch2_Lname_Fname.sql for odd number
questions on “Hands-on Assignments”. Use
appropriate COLUMN statements to produce readable
outputs
• 3. Execute and test one problem a time (do #1 at the
end, why?) and make sure they are all running
successfully. Include class and personal information.
• 4. When you done, spool the script files (see next slide
for spooling instructions) and upload SQL and the
spooled files (Oracle_ch2_Spool_Lname_Fname.txt) to
Bb by midnight this coming Sunday. Turn in a
hardcopy of spooled file (*.txt ONLY) to me in the
class.
Dr. Chen, Business Database Systems (Oracle)
How to Spool your Script and Output Files
After you tested the script file of Oracle_ch2_Lname_Fname.sql successfully,
follow the instructions below to spool both script and output files:
Step 0. Run the following two script files from SQL*Plus (since you have
created JLDB tables)
– Start c:\oradata\chapter2\JLDB_Drop.sql
– Start c:\oradata\chapter2\JLDB_Build.sql
• 1. type the following on SQL>
– Spool c:\oradata\chapter2\Oracle_ch2_Spool_Lname_Fname.txt (make sure your name
is entered)
• 2. open Oracle_ch2_Lname_Fname.sql that you already tested
• 3. copy and paste all the SQL commands (including all comments) to the
SQL*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\chapter2\ folder)
Upload the SQL and spooled files (*.sql and *.txt) to the Bb (under
“Assignments & Projects”) by the deadline.
Dr. Chen, Business Database Systems (Oracle)
59
Summary
• A basic query in Oracle 12c SQL includes the
SELECT and FROM clauses, the only mandatory
clauses in a SELECT statement
• To view all columns in the table, specify an
asterisk (*) or list all of the column names
individually in the SELECT clause
• To display a specific column or set of columns,
list the column names in the SELECT clause (in
the order in which you want them to appear)
• When listing column names in the SELECT
clause, a comma must separate column names
Dr. Chen, Business Database Systems (Oracle)
60
Summary (continued)
• A column alias can be used to clarify the contents
of a particular column; if the alias contains
spaces or special symbols, or if you want to
display the column with any lowercase letters,
you must enclose the column alias in double
quotation marks (" ")
• Indicate the table name following the FROM
keyword
• Basic arithmetic operations can be performed in
the SELECT clause
• NULL values indicate an absence of a value
Dr. Chen, Business Database Systems (Oracle)
61
Summary (continued)
• To remove duplicate listings, include either the
DISTINCT or UNIQUE keyword
• To specify which table contains the desired
columns, you must list the name of the table after
the keyword FROM
• Use vertical bars (||) to combine, or
concatenate, fields, literals, and other data
62
Dr. Chen, Business Database Systems (Oracle)
62
• End of chapter 2
Dr. Chen, Business Database Systems (Oracle)
63