Notes on Database users, Database Architecture, DDL, DML, DCL; ER Model

1. B.Tech III Sem ‘A’
DATABASE MANAGEMENT
SYSTEMS

2. Topics Covered
 Database users
 Database Architecture
 DDL
 DML

3. Student
Std_ID Name
Addr
Sec
DoB
Std_ID Name Addr Sec DoB
189X1A05XY Sree Sanfransisco A 01/01/1999
189X1A05XZ Sri Germany B+ 01/01/2000
ER Model Relational Model
ER Model Vs. Relational Model

4. Naive / Prgmers / Sophisticated / DBA
Appl.
interface
s
Appl.
programs
Query
tools
Admin
tools
Query Processor
Object
code
Compiler
DML
Queries
DDL
Interpreter
Query Evaluation Engine
Storage Manager
Buffer
Manager
File
Manager
Authorization &
integrity manager
Transaction
Manager
Data Indice
s
Data
Dictionar
y
Disk Storage
Users

5. DDL Commands
DDL:
Data Definition
Language
 CREATE
 ALTER
 DROP
 RENAME
DML:
Data Manipulation Language
 INSERT
 UPDATE
 DELETE
 SELECT
DCL:
Data Control Language
 GRANT
 REVOKE
 COMMIT (TCL)
 ROLLBACK (TCL)

6. DDL: Create
CREATE TABLE
CUSTOMER1(
ID Number(2),
NAME NVARCHAR2 (20),
AGE INT,
ADDRESS NVARCHAR2
(30) ,
SALARY DECIMAL (10, 2)
create table cust_temp as
select id, name from
customer1;
CREATE TABLE STUDENT2
(
ID INT NOT NULL,
NAME VARCHAR(20) NOT
NULL,
AGE INT NOT NULL,

7. DDL: Alter
 ALTER TABLE table_name ADD column_name
datatype;
 ALTER TABLE table_name DROP COLUMN
column_name;
 ALTER TABLE table_name MODIFY COLUMN
column_name datatype;
 ALTER TABLE table_name MODIFY column_name
datatype NOT NULL;

8. DDL Command: DROP &
Rename
 Drop table student;
 Rename student1 to student2;
 TRUNCATE TABLE customer1;

9. DML: Data Manipulation Language
 INSERT
 UPDATE
 DELETE
 SELECT

10. DML Example: Insert
insert into customer1values(90, 'Codd',60,'San Fransisco',
150000);
insert into customer1 values(&id,
'&name',&age,'&address',&salary);
SELECT * FROM EMPLOYEE
UPDATE Customer1 set ID=18, WHERE Name='henry
korth';DELETE FROM Customer1 WHERE Name='Henry Korth' AND
age=60;

11. Today’s Topics
 DCL
 Entity Relationship Model
 Basic concepts
 Cardinality of Relationship
 ER Diagram Notations
 ER Diagrams: Examples

12. DCL: Data Control Language
 GRANT : used to grant or give the privileges.
 REVOKE : used to avoid or object the privileges.
 COMMIT: used to save the data permanently.
 ROLL BACK : Used to revert changes in the
transactions since the last commit or rollback
command was issued

13. DCL: Commit
DELETE FROM
CUSTOMERS
WHERE AGE = 25;
SQL> COMMIT;

14. Rollback
 ROLLBACK command is the transactional
command used to undo transactions that have
not already been saved to the database.
 This command can only be used to undo
transactions since the last COMMIT or
ROLLBACK command was issued.
 DELETE FROM CUSTOMERS WHERE AGE =
25;

15. DCL : Grant & Revoke
create user korth identified by henry
 Connect as system/ora10g
GRANT SELECT, INSERT, UPDATE, DELETE
ON Emp_Det TO korth;
REVOKE DELETE ON Emp_details FROM

16. Entity Relationship Model
 The ER data model facilitates database design
by allowing specification of an enterprise
schema that represents the overall logical
structure of a database.
 The E-R data model employs three basic
concepts: entity sets, relationship sets, and
attributes

17. Entity Sets
 Entity: Real-world object distinguishable from other
objects. An entity is described (in DB) using a
set of attributes.
 Entity Set: A collection of similar entities. E.g., all
employees.
 All entities in an entity set have the same set of attributes.
 Each entity set has a key.
 Each attribute has a domain.

18. Entity Sets

19. Relationship Sets
 Relationship: Association among two or more
entities.
 A relationship set is a mathematical relation
among n  2 entities, each taken from entity sets
{(e1, e2, … en) | e1  E1, e2  E2, …, en 
En}
where (e1, e2, …, en) is a relationship

20. Relationship: Depositor

21. Relationship: Borrower

22. Attributes
 An entity is represented by a set of
attributes, that is descriptive properties
possessed by all members of an entity
set.Example:
customer = (customer_id, customer_name, customer_street,
customer_city )
loan = (loan_number, amount )

23. Attribute types
 Simple : Attribute is simple, if its value can not be divided into subparts.
For example Std_ID, GPA.
 Composite : Attribute is composite, if its value can be divided into
subparts. Ex: Name: First Name; Middle Name; Last Name
Address: H.No; street; city; pincode
 Single-valued : Attribute is a single-valued, if it has only one value for a
particular entity
 Multivalued : Attribute is multivalued, if it has a set of values for a
particular entity. Ex: Phone number
 Derived: Attribute is a derived, if its value can be derived from the values
of other related attributes or entities. Ex: Age, given dateofbirth

25. ER Diagram Notations
 Rectangles represent entity sets
 Ellipses represent attributes
 Diamonds represent relationship sets
 Lines link attributes to entity sets and link entity
sets to relationships sets

26. Continued…
 ER Diagram Notations
 ER Diagram Examples