CS 3630 Database Design and Implementation

Database Schema

Branch (Bno…) Staff (Sno…Bno) Owner (Ono…) PropertyForRent (Pno…Ono) Renter (Rno…) Viewing (Rno, Pno, ViewDate…)

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In what order to create the tables?

Branch (Bno…) Staff (Sno…Bno) Owner (Ono…) PropertyForRent (Pno…Ono) Renter (Rno…) Viewing (Rno, Pno, ViewDate…)

Will it work?YES!

Branch (Bno…) Staff (Sno…Bno) PropertyForRent (Pno…Ono) Owner (Ono…) Viewing (Rno, Pno, ViewDate…) Renter (Rno…)

Will it work?NO!

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Referential Integrity!

In what order to drop the tables?

Viewing (Rno, Pno, ViewDate…) Staff (Sno…Bno) PropertyForRent (Pno…Ono) Owner (Ono…) Renter (Rno…) Branch (Bno…)

Will it work?YES!

Branch (Bno…) Staff (Sno…Bno) Owner (Ono…) PropertyForRent (Pno…Ono) Renter (Rno…) Viewing (Rno, Pno, ViewDate…)

Will it work?NO!

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Referential Integrity!

Insert Rows

The PK must be unique

The foreign key value must exist in the parent table if FK is provided

FK can be null, meaning not known at the time

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Insert Rows

Insert into Branch: no problem

Insert into Staff: Cannot insert a staff with Bno being ‘B123’ if Branch table has no ‘B123’ in Bno column

FK can be null, meaning not known at the time

Branch

Bno Phone …

B101

B205

Staff

Sno Phone Bno

SG100 B101

SG363 Null

SA200 B123B123

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Delete Rows

No records in other tables referencing the record to be deleted.

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Delete Rows

Delete from Staff: no problem

Delete from Branch: Delete branch 'B101' What about staff in 'B101‘?

Branch

Bno Phone …

B101B101

B205

Staff

Sno Phone Bno

SG100 B101

SG363 Null

SA200 B101

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ANSI SQL Solutions In ANSI SQL, there are five choices

• No Action Cannot delete • Set to Null • Set to Default • No Check No good• Cascade Delete all staff in 'B101' from Staff table when deleting

branch ‘B101’ Dangerous!

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Oracle Solutions In Oracle, only two choices are implemented

• No Action

Cannot delete

• Cascade

Delete all staff in 'B101' from Staff table when deleting branch ‘B101’

• Set to Null: not implemented Set to Null: not implemented

• Set to Default : not implemented Set to Default : not implemented

• No Check : not implementedNo Check : not implemented

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Update Record

Update table Staff ‘B101’ of SG100 to ‘B205’ New value must exist in Branch

Update table Branch ‘B101’ to ‘B303’ Five choices in ANSI SQL, only No Action is implemented in Oracle

Branch

Bno Phone …

B101

B205

Staff

Sno Phone Bno

SG100 B101

SG363 Null

SA200 B205

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Integrity Rules: Constraints

• Column Constraints

• Table Constraints

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Column Constraints

• Primary key Sno Char(4) Primary Key,• Alternate Key SSN Char(9) Unique,• Foreign Key BNo char(4) References Branch, -- when attribute has the same name BNo char(4) References Branch, -- even when FK and PK have different names BNo char(4) References Branch on Delete Cascade, -- Do NOT use “Foreign Key” in column constaints!

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References

• Only for Foreign Key• Cannot reference other attributes

• Even not AKs

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Column Constraints

• Domain constraint

Salary Number Check (Salary > 10000 and Salary < 200000),

PType varchar2(6) Check (PType in ('House', 'Flat', 'Appt')),

-- Strings are in single quotes, NOT double quotes

Bno Char(4) Default 'B363' References Branch,

Rent Float Check (Rent Between 200 and 400),

-- between is Inclusive

• Required data

LName Varchar2(20) Not Null,

-- Can be specified only by column constraint

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Column Constraints

Create table Staff (

SNo char(4) Primary Key,

Bno Char(4) Default 'B363' References Branch on Delete Cascade,

FName Varchar2(20) Not Null,

LName Varchar2(20) Not Null,

-- assuming functions DateDiff and Now

DOB Date Not Null Check (DateDiff(Year, Now, DOB) >= 16),

Salary Number Check (Salary Between 30000 and 100000),

SSN Char(9) Unique,

Tel_No Char(12));

-- Primary Key, Unique, References should be the last constraint for a column

-- Do not use Foreign key for column constraints, only use References

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Table Constraints

• Constraints on one or more columns– Composite PK, AK, FK

• Cannot use Not Null in table constraints

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Table Constraints

Create table Staff (

SNo char(4),

FName Varchar2(20) Not Null,

LName Varchar2(20) Not Null,

DOB Date,

Salary Number default,

BNo Char(4),

Tel_No Char(12),

SSN Char(11),

Constraint PK_Staff

Primary Key (SNo),

Constraint Range_of_Salary

Check (Salary between 30000 and 200000),

Unique (SSN),

Foreign Key (BNo) References Branch (BNo));18

Attribute Order in Foreign Key

-- Primary key (c1, c2) for TableA

Foreign Key (c1, c2) References TableA, -- Same order as PK

Foreign Key (c2, c1) References TableA(c2, c1), -- Different order from PK

Foreign Key (c2, c1) References TableA, -- Incorrect!

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-- Composite PK

Create Table Test3 (

C1 Char(5),

C2 Varchar2(50) ,

C3 Integer,

C4 Date,

Constraint Test3_PK

Primary Key (C1, C3));

Desc Test3

pause;

Create Table Test4 (

D1 VARCHAR2(25) Primary Key,

D2 Char(5),

D3 Integer,

Constraint Test4_FK

Foreign Key (D2, D3) references Test3);

Desc Test4;

Pause

Works.Works.20

-- Composite PK

Create Table Test3 (

C1 Char(5),

C2 Varchar2(50) ,

C3 Integer,

C4 Date,

Constraint Test3_PK

Primary Key (C1, C3));

Desc Test3

pause;

Create Table Test4 (

D1 VARCHAR2(25) Primary Key,

D2 Char(5),

D3 Integer,

Constraint Test4_FK

Foreign Key (D3, D2) references Test3);

Desc Test4;

Pause

Does Not Work.Does Not Work.21

-- Composite PK

Create Table Test3 (

C1 Char(5),

C2 Varchar2(50) ,

C3 Integer,

C4 Date,

Constraint Test3_PK

Primary Key (C1, C3));

Desc Test3

pause;

Create Table Test4 (

D1 VARCHAR2(25) Primary Key,

D2 Char(5),

D3 Integer,

Constraint Test4_FK

Foreign Key (D3, D2) references Test3(C3, C1));

Desc Test4;

Pause

Works.Works.22

UserName_Lab7.sql------------------------------------------------

-- Name : Qi Yang

-- UserName : YangQ

-- Date : 03-26-14

-- Course : CS 3630

-- Description: Creating tables

-- Inserting records

------------------------------------------------

Drop Table test2;

Drop Table test1;

Create table test1 . . .

Desc Test1

Pause

Create Table Test2 . . .

Desc test2

Pause

Insert into test1 . . .

Commit;

Select *

From Test1;

. . . 23

Assignment7

Table names and column names must be exactly the same as specified.

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SQL Script File

• Using any text editor outside SQL*Plus

• File extension .SQL

UserName_Lab7.Sql• Multiple SQL commands

• Each command ends with ;

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Running Script File

• Using either Start or @

SQL> Start file_name_with_full_path

SQL> @file_name_with_full_path

• Use Arrow Keys to get previous commands!

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