INTERNAL MODEL

• Maps conceptual model to DBMS

• Represents database ‘seen’ by DBMS

• Require match conceptual model characteris�cs

and constraints to selected implementa�on

model

INTERNAL SCHEMA

• Depicts representa�on of internal model, using

database constructs

DATA DICTIONARY

• Detailed accoun�ng of all tables within user-created database

• Contains all a"ribute names and characteris�cs for each table

• Contains metadata—data about data

PARTIAL DEPENDANCE

• Dependency based on only part of composite primary key (1NF)

ATTRIBUTES

• Composite a�ribute: not composite key. A�ribute

further subdivided to yield addi�onal a�ributes

• Simple a�ribute: a�ribute cannot be subdivided

• Single-valued a�ribute: have only one value

• Mul%valued a�ribute: have many values

• Derived a�ribute: a�ribute value calculated

(derived) from other a�ributes

DATABASE TABLE NORMALIZATION

• First Normal Form (1NF) = Table format, no repea�ng groups and PK defined

• Second Normal Form (2NF) = Table 1NF, no par�al dependencies (no a"ribute dependent on por�on of primary

key)

• Third Normal Form (3NF) = Table 2NF, no transi�ve dependencies

• Boyce-Codd Normal Form (BCNF) = Table 3NF, every determinant in table candidate key

• Fourth Normal Form (4NF) = Table 3NF, no independent mul�valued dependencies

RELATIONAL SCHEMA

• Textual representa�on of database table, each table described by name, list

a"ributes in parenthesis

LECTURER (EMP_NUM, LECTURER_OFFICE, LECTURER_EXTENSION,

LECTURER_HIGH)DEGREE)

KEYS

• Primary Key (PK) = a"ribute (or combina�on) uniquely iden�fies row (not null)

• Composite key = composed more that one a"ribute

• Superkey = uniquely iden�fy each row, func�onally determines rows a"ributes

• Candidate key = Superkey without redundancies (not contain subset a"ributes, itself superkey)

• Secondary key = a"ribute (or combina�on a"ributes) used strictly for data retreival

• Foreign key = a"ribute (or combina�on a"ributes) in one table whose value match primary key in another table,

or be null

• Surrogate key = Ar�ficial PK simplifying assignment PK to table, numeric, automa�c generated, hidden from user

FUNCTIONAL DEPENDENCY

• A"ribute B func�onally dependent on A if A

determines B

• A"ribute B func�onally dependent in A if each

value in column A determines one and one one

value in column B

DESIGN CASES

• Implemen%ng 1:1 Rela%onship

⇒ Foreign key work with primary key

⇒ Primary key ‘one’ side (parent) on ‘many’ sides (dependent en�ty) of foreign key

• Maintaining history over %me and must keep history

⇒ Create 1:* rela�onship

• FAN Traps

⇒ Rela�onship improperly iden�fied, inconsistent with real world

⇒ One en�ty in two 1:* rela�onships to other en��es, produsing associa�on among other en��es

not expressed in model

• Redundant Rela%onship

⇒ Mul�ple rela�onship paths between related en��es

⇒ Remain consistent across model

PRIMARY KEY CHARACTERISTICS

• Unique value

• Cannot contain null value

• No change over �me (stable), permanent,

unchangeable

• Minimal—fewest a"ributes

• Factless—no hidden informa�on, cannot be

composed

• Numeric

• ERM = En�ty Rela�onship Model

• ERD = En�ty Rela�onship diagram

• UML = Unified Modelling Language

PARTIAL AND TOTAL COMPLETENESS

• Par%al Completeness = every supertype occurrenece is member of subtype, may be supertype occurrences not

members of subtype

• Total Completeness = every supertype occurrence must be member of at leat one subtype

ERM COMPONENTS in CRAW’s FOOT MODEL

• En%ty = person, place, thing store mul�ple instances

|——————|

| DESK |

|——————|

| * desk_id |

| desk_colour |`

| desk_size |

|——————|

|——————|

• Cardinality = indicate rules around rela�onship

->0————— zero or more

->|————— one or more

—||———— one and only one

—|0———— zero or one

• Weak en%ty = existence-dependent, primary key par�ally or totally derived from parent

en�ty.

Condi�ons met before en�ty classified as weak en�ty:

1) En�ty existence-dependent on parent en�ty

2) En�ty inherit part of primary key from parent

|——————–——-| |——————–——– |

| EMPLOYEE | | DEPARTMENT |

|——————–——-| |——————–——– |

| EMP_NUM {PK} | has > | DEP_NUM {PK} |

| EMP_NAME |—————--| EMP_NUM {PK}{FK} |

| EMP_DOB |1..1 0..* | DEP_NAM |

|——————–——-| | DEP_DOB |

|——————–——-| |——————–———|

|——————–———|

• Strong en%ty rela%onship = PK of related en�ty contains PK component of parent en�ty

|——————–——-| |——————–——– |

| COURSE | | CLASS |

|——————–——-| |——————–——– |

| CRS_CODE {PK} | generates | CRS_CODE {PK} {FK} |

| DEPT_CODE |—————--| CLASS_SECTION{PK} |

| SRS_DESCRIPTION |1..1 0..* | CLASS_TIME |

| CRS_CREDITS | | ROOM_CODE |

|——————–——-| |——————–———|

|——————–——-| |——————–———|

COURSE (SRS_CODE, DEPT_CODE, CRS_DESCRIPTION, CRS_CREDITS)

CLASS (CRS_CODE, CLASS_SECTION, CLASS_TIME, ROOM_CODE)

CARDINALITY RELATIONSHIP

• 1:1 STUDENT -||—-fills —-||- SEAT

• 1:M INSTRUCTOR -||--teaches--|<- COURSE

• M:M STUDENT ->-|—takes—|<- COURSE

• 0:N ->-0————-<-

Create Database Schema

CREATE SCHEMA AUTHORIZATION {creator};

CREATE SCHEMA AUTHORIZATION JONES;

Create Table Structure

CREATE TABLE tablename (

column1 datatype [constarint] [,

Column2 datatype [constraint] [,

PRIMARY KEY (column1 [, column2]) ] [.

FOREIGN KEY (column1 [, column2])

REFERENCES tablename ] [,

CONSTRAINT constraint ] );

CREATE TABLE VENDOR (

V_CODE INTEGER NOT NULL UNIQUE,

V_NAME VARCHAR(35) NOT NULL,

V_CONTACT VARCHAR(15) NOT NULL,

PRIMARY KEY (V_CODE) );

Adding Table Rows

INSERT INTO tablename VALUES (value1, value2, …, valueN );

INSERT INTO VENDOR VALUES (21225, ‘Bryson, Inc’, ‘Smithson’ );

Saving Table Changes

COMMIT;

Restore Table Contents

ROLLBACK;

If not yet used, COMMIT to restore changes

Lis%ng Table Rows

SELECT Columnlist FROM tablename

* (asterisk) as wildchard list all a"ributes

SELECT * FROM PRODUCT;

SELECT P_CODE, P_DESCRIPTION, P_PRICE FROM PRODUCT;

SELECT P_DESCRIPTION, P_INDATE, P_PRICE FROM PRODUCT WHERE V_CODE = 21344;

SELECT P_DESCRIPTION, P_QOH,_PMIN FROM PRODUCT WHERE P_PRICE <= 10;

SELECT P_DESCRIPTION, P_INDATE, P_PRICE FROM PRODUCT

WHERE V_CODE = 21344 OR V_CODE = 24288;

SELECT * FROM PRODUCT WHERE NOT (V_CODE = 21344);

SELECT * FROM PRODUCT WHERE P_PRICE BETWEEN 50.00 AND 100.00;

SELECT P_CODE, P_DESCRIPTION, V_CODE FROM PRODUCT WHERE V_CODE IS NULL;

SELECT V_NAME, V_CONTACT, V+PHONE FROM VENDOR WHERE V_CONTACT LIKE ‘Smith%’;

% any and all following

_ one character

DELETING Table Rows

DELETE FROM tablename [WHERE condi�onlist];

DELETE FROM PRODUCT WHERE P_CODE = ‘BRT-3’;

DELETE FROM PRODUCT WHERE P_MIN = 5;

Deleing all rows:

DELETE FROM PRODUCT;

Upda%ng Table Rows (modify data)

UPDATE tablename SET columnname = expression

[, columnname—expression]

[ WHERE condi�on];

UPDATE PRODUCT SET P_INDATE = ‘18-JAN’

WHERE P_CODE = ‘13-Q.P2’;

Logical Operators: AND, OR, NOT

SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE FROM PRODUCT

WHERE V_CODE = 21344 OR V_CODE = 24288;

SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE FROM PRODUCT

WHERE P_PRICE < 50 and P_INDATE > ‘15-JAN’;

SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE FROM PRODUCT

WHERE (P_PRICE < 50 AND P_INDATE > ‘15-JAN’)

OR V_CODE = 24288;

SELECT * FROM PRODUCT

WHERE NOT (V_CODE = 21344);

Special Operators

Between:

SELECT * FROM PRODUCT

WHERE P_PRICE BETWEEN 50.00 and 100.00;

Is Null:

SELECT P_CODE, P_DESCRIPT, V_CODE FROM PRODUCT

WHERE V_CODE IS NULL;

Like (%, _ ):

SELECT V_NAME, V_CONTACT, V_AREACODE, V+PHONE FROM VENDOR

WHERE V_CONTACT LIKE ‘Smith%’;

In:

SELECT * FROM PRODUCT

WHERE V_CODE IN (‘21344’, ‘24288’); //same as OR

Exists:

SELECT * FROM VENDOR

WHERE EXISTS (SELECT * FROM PRODUCT WHERE P_QOH < P_MIN * 2 ) ;

Changing Column Characteris%cs

Change column Data Type:

ALTER TABLE PTODUCT MODIFY (V_CODE CHAR (5) );

Changing Column Data Characteris%c:

ALTER TABLE PRODUCT MODIFY (P_PRICE DECIMAN (2,2) );

Adding Column:

ALTER TABLE PRODUCT ADD (P_SALECODE CHAR (1) );

Dropping Column:

ALTER TABLE VENDOR DROP COLUMN V_ORDER;

Copying Parts of Table

INSERT INTO PART (PART_CODE, PART_DESCRIP, PART_PRICE, VODE)

SELECT P_CODE, P_DESCRIPT, P_PRICE, V_CODE FROM PRODUCT;

Ordering Lis%ng

SELECT P_CODE, P_DESCRIPT, P_INDATE, P_PRICE FROM PRODUCT ORDER BY P_PRICE;