Oracle_ch4.pptx

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Dr. Chen, Oracle Database System (Oracle) 1

Chapter 4Constraints

Jason C. H. Chen,Ph.D.

Professor of MIS

School of BusinessGonzaga University

Spokane, WA 99258 USA

[email protected]


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What will we study today?

IntegrityData

Referential

Integrity

How to

achieve it?


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Objectives

Explain the purpose of constraints in a table

Distinguish among PRIMARY KEY, FOREIGNKEY, UNIQUE, CHECK, and NOT NULLconstraints and the appropriate use for eachconstraint

Understand how constraints can be created whencreating a table or modifying an existing table

Distinguish between creating constraints at thecolumn level and table level


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Objectives (continued)

Create PRIMARY KEY constraints for a singlecolumn and a composite primary key (cpk)

Create a FOREIGN KEY constraint

Create a UNIQUE constraint Create a CHECK constraint

Create a NOT NULL constraint using the ALTER

TABLEMODIFY command

Include constraints during table creation

Use DISABLE and ENABLE commands

Use the DROP command


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customers

orders

pk

fkpk

customer# LastName Referred Region

1001 MORALES NULL SE

1005 GIRARD NULL NW

1020 FALAH NULL NE

Order# customer# ShipZip ShipCost

1000 1005 98114 2.00

1003 1001 32328 4.00

1012 1007 49002 6.00

Can we create orders#1 if customers#5 is not

created? Why?

Can we delete customers#5 if orders#1 is still in thedatabase? Why?

Customers#5

orders#1

Referential Integrity


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Refresh the Database

1. Create a new folder on c:\ as follows:

c:\oradata\chapter4

2. Go to Blackboard and download datafiles from Oracle chapter4 and save under

c:\oradata\chapter4\

3. Run the following script file

Start c:\oradata\chapter4\JLDB_Build_4.sql


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Type the following SQL commands

-- chapter 4, Figure 4-5; p. 104INSERT INTO customers (customer#, lastname,

firstname, region)

VALUES (1020, 'PADDY', 'JACK', 'NE');

--extra INSERT command

INSERT INTO orders (order#, customer#, orderdate)

VALUES (1021, 1021, '06-APR-09');

-- DELETE command

DELETE FROM customers

WHERE customer# = 1005;


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pk

pk fk

Customers#5

orders#1

Can we create

orders#1 if

customers#5 isnot created?

Why?

Can we delete

customers#5 if

orders#1 is still in

the database?

Why?

Can we insert a

different customerwith Duplicate pk?


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customers

RULES:

1.

You cant adda record to TABLE- (or the table with fk,e.g., orders)

unless there is a corresponding record in TABLE-1 (or the table with pk).

2.You cant deletea record in TABLE-1 (or the table with pk, e.g.,

customers) if there is a record in TABLE-

(or the table with fk).

Order of enteringdata into the database: customersorders

Order of deletingdata from the database: orders customers

orders

pk

fkpk

customer# LastName Referred Region

1001 MORALES NULL SE

1005 GIRARD NULL NW

1020 FALAH NULL NE

Order# customer# ShipZip ShipCost

1000 1005 98114 2.00

1003 1001 32328 4.00

1012 1007 49002 6.00


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Review from Last Class

What are the three rules of naming table and field?

What are the three (total of four) required information

that should be described for each field?1. Name

2. Type

3. Size

4. Constraint

L


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What is a Constraint?

A rule used to enforce business rules, practices,and policies

A rule used to ensure accuracy and integrity of

data A mechanism used to protect

the relationship between data within an Oracletable, or

the correspondence between data in two differenttables.

For example, the state entered must be one of the 50

states in the U.S.


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Types of Constraints

I ntegr i ty constraints: define primary and foreignkeys

Value constraints:define specific data values ordata ranges that must be inserted into columns and

whether values must be unique or not NULL

Table constraint: restricts the data value withrespect to all other values in the table

Field (column) constraint: limits the value thatcan be placed in a specific field, irrespective ofvalues that exist in other table records


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I. Naming conventions for constraints

__

Where is:

pk PRIMARY KEY fk REFERENCES (pk)

ck CHECK (note that cc stands for CHECK CONDITION)

nn NOT NULL

uk UNIQUE

e.g.,

s_id NUMBER (6) CONSTRAINT student_s_id_pkPRIMARY KEY;


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Integrity Constraints

Define primary key fields

Specify foreign keys and theircorresponding table and columnreferences

Specify composite keys


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Creating a Table

CREATE TABLE tablename

(fieldname1data_type (size)

[CONSTRAINT constraint_name constraint_type],fieldname2 data_type (size),

[CONSTRAINT constraint_name constraint_type,]

);


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Creating Constraints

When

During table creation

After table creation, by modifying the existing

table

How

Column level approach

Table level approach


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Creating Constraints at the Column Level

If a constraint is being created at the column level, the

constraint applies to the column specified

Creating Constraints at the Table Level

Approach can be used to create any constraint type after alltable field definitions are completed except NOT NULL

Required if constraint is based on multiple columns

Figure 4-1 Syntax for creating a column-level constraint

Figure 4-2 Syntax for creating a table-level constraint


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Customer# LastName FirstName Address City State Zip Referred Region EmailNUMBER(4) VARCHAR2(10) VARCHAR2

(10)

VARCHAR2

(20)

VARCHAR2(12) VARCHAR

2(2)

VARCHAR2

(5)

NUMBER(

4)

CHAR(2) VARCHAR2(

30)

Order# Customer# OrderDate ShipDate ShipStreet ShipCity ShipState ShipZip ShipCostNUMBER(4) NUMBER(4) DATE DATE VARCHAR2(18) VARCHAR2(15) VARCHAR2(2) NUMBER(4) NUMBER(4,2)

CREATE TABLE Customers

(Customer# NUMBER(4),

LastName VARCHAR2(10) NOT NULL,

FirstName VARCHAR2(10) NOT NULL,

Address VARCHAR2(20),

City VARCHAR2(12),

State VARCHAR2(2),

Zip VARCHAR2(5),

Referred NUMBER(4),Region CHAR(2),

Email VARCHAR2(30),

CONSTRAINT customers_customer#_pk PRIMARY KEY(customer#),

CONSTRAINT customers_region_ck

CHECK (region IN ('N', 'NW', 'NE', 'S', 'SE', 'SW', 'W', 'E')) );

CUSTOMERSpk

ORDERSfkpk

Optional(variable name)


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Customer# LastName FirstName Address City State Zip Referred Region EmailNUMBER(4) VARCHAR2(10) VARCHAR2

(10)

VARCHAR2

(20)

VARCHAR2(12) VARCHAR

2(2)

VARCHAR2

(5)

NUMBER(

4)

CHAR(2) VARCHAR2(

30)


CREATE TABLE Orders

(Order# NUMBER(4),

Customer# NUMBER(4),OrderDate DATE NOT NULL,

ShipDate DATE,

ShipStreet VARCHAR2(18),

ShipCity VARCHAR2(15),

ShipState VARCHAR2(2),ShipZip VARCHAR2(5),

ShipCost NUMBER(4,2),

CONSTRAINT orders_order#_pkPRIMARY KEY(order#),

CONSTRAINT orders_customer#_fkFOREIGN KEY (customer#)

REFERENCEScustomers(customer#));

CUSTOMERSpk

ORDERS

fk

pk

Optional

(variable name)


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ORDERS

Order# Item# ISBN Quantity PaidEach

NUMBER(4) NUMBER(2) VARCHAR2(10) NUMBER(3) NUMBER(5,2)

ORDERITEMS

CREATE TABLE ORDERITEMS

( Order# NUMBER(4),

Item# NUMBER(2),

ISBN VARCHAR2(10),

Quantity NUMBER(3) NOT NULL,

PaidEach NUMBER(5,2) NOT NULL,

CONSTRAINT orderitems_order#item#_pkPRIMARY KEY (order#,

item#),CONSTRAINT orderitems_order#_fkFOREIGN KEY (order#)

REFERENCESorders (order#) ,

CONSTRAINT orderitems_isbn_fkFOREIGN KEY (isbn)

REFERENCESbooks (isbn) ,

CONSTRAINT oderitems_quantity_ckCHECK(quantity > 0) );

ISBN Title PubDate PubID Cost Retail Discount CategoryVARCHAR2(10) VARCHAR2(30) DATE NUMBER(2) NUMBER(5,2) NUMBER(5,2) NUMBER(4,2) VARCHAR2(12)

BOOKSpk

fkfk

pk

Optional

(variable name)

cpk

How to define composite key?


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Your Job

You need to study and understand all

CREATE TABLE SQL commands in

JLDB_Build_4.sql


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Enforcement of Constraints

All constraints are enforced at the table

level

If a data value violates a constraint, the

entire row is rejected


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Constraint Types

Table 4-1 Constraint types


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Your Turn


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Syntax:CONSTRAINT constraint_name PRIMARY KEY

Primary Key Constraints

SQL> CREATE TABLE students

2 (s_id NUMBER(6) CONSTRAINT students_s_id_pk PRIMARYKEY,

3 s_name VARCHAR2(30),

4 s_class CHAR(2),

5 s_dob DATE);

Create a table with the following information:

1. Name of the table: students

2. Fields: s_id number with 6 digits and is a primary key, s_namecharacter with 30 chars, s_class with 2 chars, s_dob with DATE


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at the Column-Level

Primary Key Constraints (cont.)


2 (s_id NUMBER(6),3 s_name VARCHAR2(30),

4 s_class CHAR(2),

5 s_dob DATE,

6 CONSTRAINT students_s_id_pkPRIMARY KEY (s_id));


2 (s_id NUMBER(6) CONSTRAINT students_s_id_pkPRIMARY

KEY,

3 s_name VARCHAR2(30),

4 s_class CHAR(2),

5 s_dob DATE);

Practice:

Type in one of the command. at the Table-Level


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Adding Constraints to Existing Tables

Constraints are added to an existing table

with the ALTER TABLE command

Add a NOT NULL constraint using

MODIFY clause

All other constraints are added using ADD

clause


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Using the PRIMARY KEY Constraint

Ensures that columns do not contain duplicate

or NULL values

Only one per table is allowed

Figure 4-3 Syntax of the ALTER TABLE command to add a PRIMARY KEY constraint


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Constraint Checked with Data Input

Figure 4-5 Insert a row to test the constraint


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PRIMARY KEY Constraint for Composite Key

List column names within parentheses

separated by commas

Figure 4-7 Adding a composite PRIMARY KEY constraint


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Drop Contraint

ALTER TABLE orderitems

DROP CONSTRAINT

orderitems_order#item#_pk PRIMARY

KEY (order#, item#);


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Multiple Constraints on a Single Column

A column may be included in multiple constraints

The order# column is included in a primary key and a

foreign key constraint

Figure 4-32 Assigning multiple constraints to a column

Optional

(variable name)


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Using the FOREIGN KEY Constraint

Requires a value to exist in the referenced column

of another table

NULL values are allowed

Enforces referential integrity Maps to the PRIMARY KEY in parent table

Customer# LastName FirstName Address Region

Order# Customer# OrderDate ShipZip ShipCost

customers

orders

pk

fk


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Using the FOREIGN KEY Constraint

You cannot delete a value in a parent table (pk)

referenced by a row in a child table (fk)



customers

orders

pk

fk


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customers

orders

pk

fk

RULES:

1.

You cant adda record to TABLE- (or the table with fk,

e.g., orders) unless there is a corresponding record in

TABLE-1 (or the table with pk).

2.You cant deletea record in TABLE-1 (or the table with pk, e.g.,

customers) if there is a record in TABLE- (or the table with fk).

Order of enteringdata into the database: customersorders

Order of deletingdata from the database: orders customers


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FOREIGN KEY Constraint Example

Figure 4-9 Adding a FOREIGN KEY constraint


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Deletion of Foreign Key Values

You cannot delete a value in a parent table

referenced by a row in a child table

Use ON DELETE CASCADE keywords

when creating FOREIGN KEY constraintit automatically deletes a parent row when

the row in a child table is deleted


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Using the UNIQUE Constraint

No duplicates are allowed in the referencedcolumn

NULL values are permitted

Figure 4-16 Adding a UNIQUE constraint


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Using the CHECK Constraint

Updates and additions must meet specifiedcondition

Figure 4-19 Adding a CHECK constraint to the ORDERS table


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Using the NOT NULL Constraint

The NOT NULL constraint is a special

CHECK constraint with IS NOT NULL

condition

Can only be created at column level

Included in output of DESCRIBE command

Can only be added to an existing table using

ALTER TABLEMODIFY command


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NOT NULL Constraint Example

Figure 4-23 Adding a NOT NULL constraint


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Practice

Lets try to create additional tablesJustLee Books would like to create some new

tables to store office equipment inventory data.

DeptID

Dname

Fax

DEPTEquipID

Edesc

Purchdate

Rating

DeptID

EtypeID

EQUIP

EtypeID

Etypename

ETYPES

Figure 4-26 E-R model for equipment tables


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Including Constraints during Table

DeptID

Dname

Fax

DEPT EquipIDEdesc

Purchdate

Rating

DeptID

EtypeID

EQUIP

EtypeID

Etypename

ETYPES

Each department name must be unique.

Each department must be assigned a name .

Each equipment type name must be unique

Each equipment type must be assigned a name.

Each equipment item must be assigned a valid department.

If an equipment item is assigned a type, it must be a valid type.

Valid rating values for equipment are A, B, and C.

unique

NOT NULL

unique

NOT NULL

ck

fkfk

pkpk pk


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-- chapter 4, Figure 4-27; p. 117CREATE TABLE dept

(deptid NUMBER(2),

dname VARCHAR2(20) NOT NULL,

fax VARCHAR2(12),CONSTRAINT dept_deptid_pk PRIMARY KEY(deptid),

CONSTRAINT dept_dname_uk UNIQUE(dname) );

DEPT table creation

Each department name must be unique.

Each department must be assigned a name .

unique

NOT NULL

i i iff f i


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-- chapter 4, Figure 4-27; p. 117CREATE TABLE dept

(deptid NUMBER(2),

dname VARCHAR2(20) NOT NULL,

fax VARCHAR2(12),

CONSTRAINT dept_deptid_pk PRIMARY KEY(deptid),CONSTRAINT dept_dname_uk UNIQUE(dname) );

-- chapter 4, Figure 4-30; p. 119

CREATE TABLE dept(deptid NUMBER(2) CONSTRAINT dept_deptid_pk PRIMARY KEY,

dname VARCHAR2(20) NOT NULL CONSTRAINT dept_dname_uk

UNIQUE,

fax VARCHAR2(12));

Constraints are defined at the column-level

What is the main difference on the following

CREATE TABLE statements?

Constraints are defined at the table-level


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CREATE TABLE etypes

(etypeid NUMBER(2),

etypename VARCHAR2(20) NOT NULL,

CONSTRAINT etypes_etypeid_pk PRIMARY KEY (etypeid),

CONSTRAINT etypes_etypename_uk UNIQUE(etypename) );


CREATE TABLE equip

(equipid NUMBER(3),edesc VARCHAR2(30),

purchdate DATE,

rating CHAR(1),

deptid NUMBER(2) NOT NULL,

etypeid NUMBER(2),

CONSTRAINT equip_equipid_pk PRIMARY KEY(equipid),CONSTRAINT equip_deptid_fk FOREIGN KEY(deptid)

REFERENCES dept (dept_id),

CONSTRAINT equip_etypeid_fk FOREIGN KEY(etypeid)

REFERENCES etypes (etypeid),

CONSTRAINT equip_rating_ck CHECK(rating IN('A', 'B', 'C', 'D')) );

Each equipment item must be assigned a valid department.

If an equipment item is assigned a type, it must be a validtype.

Valid rating values for equipment are A, B, and C.

Each equipment type name must be unique

Each equipment type must be assigned a name.


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Including Constraints during Table CreationTable Level

Include at end of column list

Figure 4-29 EQUIP table creation


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Viewing ConstraintsUSER_CONSTRAINTS

Display constraint listing for a specific table

Figure 4-33 SELECT statement to view data about existing constraints


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Disabling Constraints

-- chapter 4, Figure 4-36; p. 123ALTER TABLE equip

DISABLE CONSTRAINT equip_rating_ck;

ALTER TABLE equip

ENABLE CONSTRAINT equip_rating_ck;


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Dropping Constraints


ALTER TABLE equip

DROP CONSTRAINT equip_rating_ck;

-- chapter 4, Figure 4-39; p. 125ALTER TABLE customers

DROP PRIMARY KEY;

-- chapter 4, Figure 4-40; p. 125ALTER TABLE customers

DROP PRIMARY KEY CASCADE;

HW!!


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HW!!

Practice all the examples in the text.

A Script file is available on the Bb (file name:

Ch4Queries.sql)

After completing all examples, do the HW (hint: see

the tables below for the final schema and the sample

output on the Bb under Assignmentsrep_id last first comm base_salary

NUMBER(5) VARCHAR2(15) VARCHAR2(10) CHAR(1) NUMBER(7,2)

store_id name contact rep_id

NUMBER(8) VARCHAR2(30) VARCHAR2(30) NUMBER(5)

store_id name quarter rep_id

NUMBER(8) VARCHAR2(5) CHAR(3) NUMBER(5)

pk store_reps

pk fkbook_stores

cpk, fkcpk

cpk, fkrep_contracts

Homework Hands On Assignments


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Homework - Hands-On Assignments

Read and Practice all examples on Chapters 4

1. Run the script files (in the folder \oradata\chapter4\):

JLDB_Build_4.sql 2. Read Oracle assignment and create a script fileOracle_ch4_Lname_Fname.sql for questions (#1 to#8; p.133) on Hands-on Assignments. .

3. Execute and test one problem at a time and make surethey are all running successfully.

4. When you done, spool the script files (see next slidefor spooling instructions) and email the file(Oracle_ch4_Spool_Lname_Fname.txt) to me by themidnight before the next class.

Email me with one attachment

(Oracle_ch4_Spool_Lname_Fname.) to:

[email protected] subject title of

bmis441_Oracle_ch4

H S l S i d O Fil


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How to Spool your Script and Output Files

After you tested the script file of Oracle_ch4_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 createdJLDB tables)

Start c:\oradata\chapter4\JLDB_Build_4.sql

1. type the following on SQL> Spool c:\oradata\Oracle_ch4_Spool_Lname_Fname.txt(make sure your name is entered)

2. open Oracle_ch4_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 andtheir solution on the .txt file and saved in C: drive (oradata\ folder)

Email me with the spooled file (.txt) with attachment to:

[email protected]

with subject title of

bmis441_Oracle_ch4


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End of chapter 4

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