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DATABASE
Management Systems
CSE3DMS
Lecture 1
Review SQL & Database
storage
Copyright © La Trobe University
Topics
• Subject information
– Subject Objectives
– Subject organization
– Class materials
– Assessment & Requirements for passing
CSE3DMS
– Lab Allocation
– Staff
• Lecture 1: Review SQL programming
2
Objectives
• Building on the grounding gained in CSE2DBF
(DATABASE Foundations), to further develop a
greater understanding of database programming in
Oracle SQL and database management system
implementation :
– to extend skills of sound database development
practices;
– to gain knowledge of principles and techniques for
implementation of database management systems;
– to understand index structures, query
optimization and transaction management for
design of database management system.
3
Subject Organization
• Credit Points:15 for 12 weeks
• Class Requirements
– On Two -hour lecture per week
• Wed 2-4:00pm in room Hooper LT
– 2 hours of tutorials/lab work per week
• Oracle11g programming - review
– Lab & assignment
• Database management systems - 11 lectures
– lectures , Tutorials, assignment & exam
4
Class Materials
Theoretical:
1. Textbook:
Database systems
Models, languages, design, and application
programming, Elmarsri & Navathe, 6th
Edition, Addison Wesley ,
http://search.lib.latrobe.edu.au/LATROBE:All:Almalu21169496160002146
2. Reference books
Database System Concepts 4- 6th Ed.
Silberschatz, Korth and Sudarshan
http://search.lib.latrobe.edu.au/LATROBE:All:Almalu21161516840002146
3. Programming
• Guide to ORACLE10g, Morrison & Morrison,
Thomson Course technology, 2006, ISBN
0619216298
http://search.lib.latrobe.edu.au/LATROBE:In_the_Library:Almalu211590750
50002146
5
Class Materials
•
–
–
–
–
–
LMS:
https://lms.latrobe.edu.au/login/index.php
Subject Leaning Guide
News
Lecture notes
Lab instructions are available on the Subject
web site
• Some supplement Lab data files are
available from the LMS
• 11 laboratory sessions.
Oracle documents related to lab questions 6
Assessment
1.
Weekly lab work 20% for 10 weeks
(each week earns 2 marks from week 2-11)
2. assignment 30%(50% )
–
–
–
–
Assignment 30% - general for all
Group Assignment (2)
TBA (Mon 10:00am)
Design and implementation SQL
3. Exam 50% (50% exam hurdle)
– CSE3DMS 2-hour examination (120)
SAH-E (hurdle supplementary in Jul)
Must prepare your time for this sup when you
have failed the exam hurdles
7
Assessment
• laboratory attendance for supplementary
hurdle
• To pass, a student must receive at least 50%
overall, and pass the hurdle requirement:
50% for the final examination
• Policy on plagiarism
http://latrobe.libguides.com/academic-integrity/ethical_use
8
Laboratory allocation
• You need to attend the Lab class and you
may only attend your allocated laboratory
session.
• Please go the following link to enroll one lab
class. (this year, we can have only one lab)
Laboratory
Monday
Tuesday
Time
11.00 - 1.00pm
11.00 - 1.00pm
Room
BG115
BG114
9
Staff
• Lecturers:
Dr Jinli Cao, Room: BG217, Phone:3035
Email: [email protected]
Consultation time: Tues 4-6pm
• Tutor:
Christopher Tao
10
Lecture 1
• Client/Server Databases & the
Oracle11g Relational Database
• Review SQL Programming
• Disk Storage, Basic File Structures, and
Hashing
•
•
Reading: the textbook Chapter 1 -3 by Morrison
Refer to Fundamentals of Database System by Elmasri & Navathe Chapter16
11
Types of Database Systems
• Personal databases (DBMS)
– DBMS and database applications run on the same
workstation
– used primarily for creating single-user database
applications
– Support small multiuser database applications by
storing the database application files on a file server
instead of on a single user’s workstation
• Client/server database
– DBMS server process runs on one workstation, and
the database applications run on separate client
workstations across the network
12
Client/Server Database Management
Systems
• Client/server database
– Clients computer runs user interface programs and
database applications
• that retrieve and manipulate small amounts of
data from database through server
– Database system at Server side stores large
numbers of records and management that serves to
clients and maintain the consistency of databases.
• There are 2-tier or 3-tier client/server architecture of
DBMS
• Organizations generally use a client/server database if
the database will have more than 10 simultaneous
users
13
Client/Server Database Architecture
14
The Oracle11g Client/Server Database
• Oracle11g is the latest release of Oracle Corporation’s
relational database
• All Oracle server- and client-side programs use Oracle
Net, a utility that enables the network communication
between the client and the server
23
11g
15
Client-Side Utilities
• SQL*Plus
– for creating and testing command-line SQL queries and
executing PL/SQL procedural programs
• Oracle SQL Developer
– free integrated development environment that simplifies the development and
management of Oracle Database. It offers complete end-to-end development of
your PL/SQL applications, a worksheet for running queries and scripts, a DBA
console for managing the database, a reports interface, a complete data
modelling solution, and a migration platform for moving your 3rd party
databases to Oracle
• Oracle10g Developer Suite
for developing database applications including the following Developer tools:
– Forms Builder
• for creating custom user applications
– Reports Builder
• for creating reports for displaying, printing, and distributing summary data
• Enterprise Manager
– for performing database administration tasks such as creating new
user accounts and configuring how the DBMS stores and manages data
16
What we have learned --SQL
•
•
•
•
Structured Query Language (SQL)
Define Oracle11g database schemas
Create database tables using SQL*Plus
Modify and delete database tables using
SQL*Plus
• Debug Oracle11g SQL commands and use
Oracle Corporation online help resources
• View information about your database tables
using Oracle11g data dictionary views
17
Structured Query Language
• The standard query language for
relational databases
• Data definition language (DDL)
– Create new database objects
– Modify or delete existing objects.
• Data manipulation language (DML)
– Insert, update, delete, and view
database data.
18
Data dictionary
• Data dictionary: tables that contain
information about the structure of the
database.
– USER: shows the objects in the current user’s
schema
– ALL: shows both objects in the current user’s
schema and objects that the user has privileges to
manipulate
Eg. User_tables, all_tables, user_constraints, etc
19
Viewing Tables in the Database
• If you want to know the structures of the Database, to view
user_tables & all_tables
20
Viewing Constraints on One Table
• View constraints of Faculty table from
user_constraints table
21
Create Synonyms & Copy tables
• A synonym can provide an alias to any object, in any
schema in a database, assuming that the user has
privileges to view the underlying objects
– It makes an object appear as if you own it,
because you do not have to use a schema prefix
when querying or performing other tasks with the
object
CREATE [ OR REPLACE ] [ PUBLIC ] SYNONYM
<schema>.<synonymname>
FOR [<schema>.]<objectname>[@<databaselinkname>];
DROP [ PUBLIC ] SYNONYM <schema>.<synonymname> [ FORCE
];
• Example: DBA can do this:
CREATE PUBLIC SYNONYM customers FOR jinli.customer;
Every user in the same database can use customers to view it.
SQL> create Table orders As Select * From jinli.orders;
22
Data Dictionary Information on
Views, Sequences, and Synonyms
• Three views are of interest:
– ALL_VIEWS
• VIEW_NAME
• TEXT
– ALL_SEQUENCES
– ALL_SYNONYMS
More on users data dictionary
– user_objects
– user_source
– user_errors
23
Deleting Table Rows
ERROR:
– Cannot delete row if it has child row –
– Other table use this record
24
Deleting Table Rows (continued)
• Child row
– Row’s value is foreign key
– Cannot delete row if it has child row
• Unless first delete the row in which foreign key
value exists
• TRUNCATE syntax
– TRUNCATE TABLE tablename;
• Cannot truncate table with foreign key
constraints
– Must disable constraints first
Guide to Oracle 10g
25
Clearwater Traders Table Relationships
•Understand
constraints of
the database.
•Can you drop
table inventory?
26
Truncate tables and Alter Constraints
• To delete a table: DROP TABLE (data and
table)
• To keep the table but delete the data use the
TRUNCATE TABLE command.
Not: before you truncate a table you have to disable
foreign key constraints
27
Truncate tables and Alter Constraints
• For Example: If you want to delete all data from table
Inventory you have to disable the foreign key
constraints inv_id from the tables order_line &
shipment_Pline
ALTER TABLE order_line
DISABLE CONSTRAINT order_line_inv_id_fk;
ALTER TABLE shipment_line
DISABLE CONSTRAINT shipment_line_inv_id_fk;
TRUNCATE TABLE Inventory;
After you have populated a new table inventory :
ALTER TABLE order_line
ENABLE CONSTRAINT order_line_inv_id_fk;
Or
MODIFY CONSTRAINT order_line_inv_id_fk ENABLE VALIDATE
28
Creating Transactions and Committing
New Data
• Transaction: series of action queries that may
change the database; it is a logical unit of work
• User can commit (save) changes
• User can rollback (discard) changes
• Pending transaction: a transaction waiting to be
committed or rolled back
• Oracle DBMS locks records associated with pending
transactions
• Other users cannot view or modify locked records
29
Commit and Roll Back in SQL*Plus
• Transactions begin automatically with first
command
• Type COMMIT to commit changes
• Type ROLLBACK to roll back changes
30
Savepoints
• A bookmark that designates the beginning of
an individual section of a transaction
• Changes are rolled back to savepoint
31
Creating New Sequences
• CREATE SEQUENCE command
– DDL command
– No need to issue COMMIT command
– Sequences are used to contain automated
counter values, most commonly used to retain
counter values for integer-valued primary keys
Guide to Oracle 10g
32
Sequences
• Syntax:
CREATE SEQUENCE <schema>.<sequencename>
[ START WITH <n> ]
[ INCREMENT BY <n> ]
[ [ NO ] MINVALUE <n> ]
[ [ NO ] MAXVALUE <n> ]
[ [ NO ] CYCLE ]
[ [ NO ] CACHE <n> ]
[ [ NO ] ORDER ];
DROP SEQUENCE <schema>.<sequencename>
Example:
CREATE SEQUENCE loc_id START WITH 1;
A sequence allows for generation of unique, sequential
values.
33
Using Sequences
• Pseudocolumn
– Acts like column in database table --DUAL
– Actually command that returns specific value
• CURRVAL
– Returns most recent sequence value retrieved
• NEXTVAL
– Next available sequence value
sequence_name.NEXTVAL
Guide to Oracle 10g
34
Using Sequences (continued)
• DUAL
– Simple table in system user schema
– More efficient to retrieve pseudocolumns from
DUAL
SELECT sequence_nm.NEXTVAL
FROM DUAL;
Example 
SELECT loc_id.NEXTVAL FROM DUAL;
Increase value in each time to read loc_id
--move value to next
SELECT loc_id.CURRVAL FROM DUAL;
Guide to Oracle 10g
35
Using Sequences
Example:
SELECT loc_id.NEXTVAL FROM DUAL;
INSERT INTO location (LOC_ID) VALUES(loc_id.NEXTVAL);
• DUAL is a table in the SYSTEM USER SCHEMA.
• You can delete the sequence by drop command
36
Viewing Sequence Information
• Query USER_SEQUENCES data dictionary view
– sequence_name column displays sequence
names
SELECT sequence_name
FROM user_sequences;
Guide to Oracle 10g
37
Grant Sequences
• Grant all privileges to all database users
for the sequence created
GRANT ALL ON loc_id_sequence TO PUBLIC
38
Modifying the SQL*Plus Display
Environment
• SQL*Plus page consists of:
– Specific number of characters per line
– Specific number of lines per page
• linesize property
– Specifies how many characters appear on line
• pagesize property
– Specifies how many lines appear on page
• Example:
SET linesize 200
SET pagesize 100
Guide to Oracle 10g
39
Modifying the SQL*Plus Display
Environment
You can change
the window size
on SQL*Plus
window
SQL*Plus command:
SET WRAP OFF
will truncate rows
if longer than the
screen width
40
What is AFIEDT.BUF?
It is the SQL*Plus default edit save file.
•Issue the command "ed" or "edit" only, the last SQL or
PL/SQL command will be saved to a file called
AFIEDT.BUF and opened in the default editor.
•Select an editor before using this command
DEFINE _EDITOR=notepad
•The buffer file “afiedt.buf”appears, when type “ed”:
SQL> ed -- enter “/” to run the command.
41
What is AFIEDT.BUF?
You can overwrite the default edit save file's name like
this:
SQL> SET EDITFILE “c:\sqlspool\buffer.sql”
SQL> Ed “c:\sqlspool\buffer.sql”
The system will call the file in your default editor
(notepad).
You can work on your code in the editor and paste it to
SQL*Plus window to run.
Close the editor and click the pop “save” for the
commands in the editor. Return back SQL*plus
Rerun the query with the slash (/) command:
42
Formatting SQL*Plus Reports
can define a more useful column heading with the
HEADING clause of the COLUMN
Syntax:
COLUMN column_name HEADING column_heading
Examples
COLUMN S_LNAME HEADING 'LAST NAME Melbourne'
COLUMN S_DOB HEADING ‘BIRTHDAY’
SELECT S_LNAME, S_DOB
FROM STUDENT WHERE CITY = ‘Melbourne';
Splitting a Column Heading
COLUMN S_LNAME HEADING 'LAST NAME |Melbourne'
43
Formatting SQL*Plus Reports
Original
Column
Headings
Changed
Column
Headings
Split
Column
Headings
You can change
the underline
with + using
SET UNDERLINE +
44
Formatting SQL*Plus Reports
Changing the
Default Display
COLUMN s_LAST
is cut with 8 char
Split COLUMN
s_LAST into 2
rows
COLUMN s_LAST FORMAT A8
45
Content
• Storage of databases
– Disk Storage Devices
• Records, Blocks, Files, Files of
Records
• Unordered Files
• Ordered Files
Refer to textbook: Database systems
Models, languages, design, and application programming, Elmarsri &
Navathe, 6th Edition, Addison Wesley
46
Storage of Databases
• The collection of data must be stored physically on some
computer storage medium.
• Computer storage media form a storage hierarchy that includes
two main categories:
1. Primary storage. can be operated directly by the computer’s
central processing unit (CPU), such as the computer’s main
memory and smaller but faster cache memories.
2. Secondary and tertiary storage. Magnetic disks, optical disks
(CD-ROMs, DVDs, and other similar storage media), and tapes.
Hard-disk drives are classified as secondary storage, whereas
removable media such as optical disks and tapes are
considered tertiary storage.
Data in secondary or tertiary storage cannot be processed
directly by the CPU; first it must be copied into primary storage
and then processed by the CPU.
47
Storage of Databases
• Preferred secondary storage device for high
storage capacity and low cost.
• Data stored as magnetized areas on
magnetic disk surfaces.
• A disk pack contains several magnetic disks
connected to a rotating spindle.
• Disks are divided into concentric circular,
Each circle is called a track
• various surfaces in a disk pack are called a
cylinder
• The number of tracks on a disk ranges from a few hundred to a
few thousand, and the capacity of each track typically ranges
from tens of Kbytes to 150 Kbytes.
48
Disk Storage Devices (cont.)
49
Disk Storage Devices (cont.)
• A track is divided into smaller blocks or sectors
• The division of a track into sectors is hard-coded on
the disk surface and cannot be changed.
– One type of sector organization shown in Fig
16.1(a) calls a portion of a track that subtends a
fixed angle at the center as a sector. Fig 16.1 (b) is
another type of organization.
• A track is divided into blocks.
– The block size B is fixed for each system during
initialization.
• Typical block sizes range from B=512 bytes to B=4096
bytes.
– Whole blocks are transferred between disk and
main memory for processing.
50
Disk Storage Devices (cont.)
51
Disk Storage Devices (cont.)
• A read-write head moves to the track that contains the
block to be transferred.
– Disk rotation moves the block under the read-write
head for reading or writing.
• A physical disk block (hardware) address consists of:
1. a cylinder number (imaginary collection of tracks of same
radius from all recorded surfaces)
2. the track number or surface number (within the cylinder)
3. and block number (within track).
• Reading or writing a disk block is time consuming
because of the seek time s and rotational delay (latency)
rd.
• Double buffering can be used to speed up the transfer of
contiguous disk blocks.
52
Records
• Fixed and variable length records
• Records contain fields which have values of
a particular type
– E.g., amount, date, time, age
• Fields themselves may be fixed length or
variable length
• Variable length fields can be mixed into one
record:
– Separator characters or length fields are needed
so that the record can be “parsed.”
53
Blocking
• Blocking:
– Refers to storing a number of records in one
block on the disk.
• Blocking factor (bfr) refers to the number of
records per block.
• There may be empty space in a block if an
integral number of records do not fit in one
block.
• Spanned Records:
– Refers to records that exceed the size of one or
more blocks and hence span a number of blocks.
54
Files of Records
• A file is a sequence of records, where each record is
a collection of data values (or data items).
• A file descriptor (or file header) includes information
that describes the file, such as the field names and
their data types, and the addresses of the file blocks
on disk.
• Records are stored on disk blocks.
• The blocking factor bfr for a file is the (average)
number of file records stored in a disk block.
• A file can have fixed-length records or variablelength records.
55
Files of Records (cont.)
• File records can be unspanned or spanned
– Unspanned: no record can span two blocks
– Spanned: a record can be stored in more than one block
• The physical disk blocks that are allocated to hold
the records of a file can be contiguous, linked, or
indexed.
• In a file of fixed-length records, all records have the
same format. Usually, unspanned blocking is used
with such files.
• Files of variable-length records require additional
information to be stored in each record, such as
separator characters and field types.
– Usually spanned blocking is used with such files.
56
Unordered Files
• Also called a heap or a pile file.
• New records are inserted at the end of the
file.
• A linear search through the file records is
necessary to search for a record.
– This requires reading and searching half the file
blocks on the average, and is hence quite
expensive.
• Record insertion is quite efficient.
• Reading the records in order of a particular
field requires sorting the file records.
57
Ordered Files
• Also called a sequential file.
• File records are kept sorted by the values of an
ordering field.
• Insertion is expensive: records must be inserted in
the correct order.
– It is common to keep a separate unordered overflow
(or transaction) file for new records to improve
insertion efficiency; this is periodically merged with
the main ordered file.
• A binary search can be used to search for a record
on its ordering field value.
– This requires reading and searching log2 of the file
blocks on the average, an improvement over linear
search.
• Reading the records in order of the ordering field is
quite efficient.
58
Ordered
Files
(cont.)
59
Average Access Times
• The following table shows the average
access time to access a specific record for a
given type of file:
60
Summary
•
•
•
•
•
Disk Storage Devices
Files of Records
Operations on Files
Unordered Files
Ordered Files
61
Next Lecture
• Next lecture Indexes.
62
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