CS 3630 Database Design and Implementation

Database Schema Branch (Bno…) Staff (Sno…Bno) Owner (Ono…) PropertyForRent (Pno…Ono) Renter (Rno…) Viewing (Rno, Pno, ViewDate…) 2

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! 3 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! 4 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 5

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 BnoPhone… B101 B205 Staff SnoPhoneBno SG100B101 SG363Null SA200 6

Delete Rows No records in other tables referencing the record to be deleted. 7

Delete Rows Delete from Staff: no problem Delete from Branch: Delete branch 'B101' What about staff in 'B101‘? Branch BnoPhone… B205 Staff SnoPhoneBno SG100B101 SG363Null SA200B101 8

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! 9

Oracle Solutions 10

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 BnoPhone… B101 B205 Staff SnoPhoneBno SG100B101 SG363Null SA200B205 11

Integrity Rules: Constraints Column Constraints Table Constraints 12

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! 13

References Only for Foreign Key Cannot reference other attributes Even not AKs 14

Column Constraints Domain constraint Salary Number Check (Salary > and Salary < ), 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 15

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 and ), 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 16

Table Constraints Constraints on one or more columns –Composite PK, AK, FK Cannot use Not Null in table constraints 17

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 and ), 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! 19

-- 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; PauseWorks. 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. 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; PauseWorks. 22

UserName_Lab7.sql Name : Qi Yang -- UserName : YangQ -- Date : Course : CS 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. 24

SQL Script File Using any text editor outside SQL*Plus File extension.SQL UserName_Lab7.Sql Multiple SQL commands Each command ends with ; 25

Running Script File Using either Start SQL> Start file_name_with_full_path Use Arrow Keys to get previous commands! 26