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Er. Pradip Kharbuja
Topic 10Supporting Transactions
Draw an ERD for a Boat Rental System
The requirements are the following:
1. You should be able to record that a boat is rented to a customer for a set period.
2. Any damage to the boat is recorded against the particular rental.
3. A boat should have a name.
4. All boats are of the same type (yacht).
5. Damage is classified as being hull, interior or other.
Draw an ERD for a Boat Rental System
The requirements are the following:
1. You should be able to record that a boat is rented to a customer for a set period.
2. Any damage to the boat is recorded against the particular rental.
3. A boat should have a name.
4. All boats are of the same type (yacht).
5. Damage is classified as being hull, interior or other.
ERD for a Boat Rental System
BOAT RENTAL CUSTOMER
DAMAGE
0...N 0...N
0...N
1
1
1
What is a Business Rule?
A rule of doing something that applies to a particular business is a Business Rule.
Business rule is enforced with a check constraint.
Transactions
A transaction is an operation carried out on the database.
Transactions can generally be identified as retrievals, inserts, updates and deletes. This is remembered by the acronym CRUD (Create, Retrieve, Update and Delete).
Transactions can be made up of one or more operations.
Identify Transactions
What do they do?
What tables do they affect?
What attributes do they affect?
How often do they run?
How many rows do they affect?
Transactions of Appointment System
Transaction 1 – Add a new patient
Transaction 2 – Delete a patient
Transaction 3 – Record a appointment
Transaction 4 – Show a detail list of patient and the appointments they have had with the doctors
Transaction 5 – Show a list of patients
Transaction 6 – Update a patient record to change their address
The tables required for this system are Patient, Appointment and Doctor.
CRUD Matrix of Appointment System (Blank)
TransactionRelation
Patient Appointment Doctor
T1
T2
T3
T4
T5
T6
CRUD Matrix of Appointment System
TransactionRelation
Patient Appointment Doctor
T1 C
T2 D
T3 C
T4 R R R
T5 R
T6 U
Transactions in the Boat Hire System
a. Enter the details of all the boats. Update any details for boats. Delete boats.
b. Enter the details for customers. Update any details for customers.
c. Enter the details for hiring of boats.
d. Enter the details for any damage to boats.
e. List the details of all the boats.
f. List the details of all the customers; their hire and for which boats.
g. List the details for damage, to which boats, during which hire periods and for which customers.
h. Provide a summary of the hires for a particular period.
TransactionRelation
Boat Customer Hire Damage
A
B
C
D
E
F
G
H
Blank CRUD Matrix
TransactionRelation
Boat Customer Hire Damage
A C U D
B C U
C C
D C
E R
F R R R
G R R R R
H R
Completed CRUD Matrix
Literary agent
Fill in the CRUD matrix below to show the following transactions.
Transaction 1. Add a new Author.
Transaction 2. Create a new agent and set up an appointment for her.
Transaction 3. Delete an author and all the appointments they have had.
Transaction 4. Show a list of Agents details and the Appointments they have had and with which Authors.
Transaction 5. Update an Agent’s address
Transaction 6. Delete an Appointment.
Performance
The term ‘Performance’ is generally used by database professionals to refer to the way in which a query behaves when run against a database.
Increasingly, databases contain large amounts of data...
The rate at which a query can return an answer can be slowed when it has to sort though large numbers of records.
Performance becomes an issue...
Indexes
An index is a structure in a database that helps queries run more quickly.
An index is a data structure that stores the values for a specific column in a table that makes easier to find a record.
Improves performance
Index can also be unique which will prevent a duplicate value from being added to that column.
Roles in a System
Not every user is the same.
Users will need to access different parts of the system and access it in different ways.
Boat Hire System - Roles
Manager – should be able to access all parts of the system, because their role means that they might have to add and delete any data and be able to see anything.
Admin Assistant – just carries out routine tasks, such as adding any new customers and recording damage to boats.
Table/User Boat Customer Rental Damage
Manager CRUD CRUD CRUD CRUD
Admin
Assistant
R CRU CRU CRU
SQL Facilities to Manage Roles
Grant – gives a particular role or user in the database system access to an object (such as a table).
Revoke – removes access to an object (such as a table) from a particular role or user in the database system.
Grant
GRANT CREATE ON Boat TO Admin;
This command will give the role of Admin the right to create data on the table Boat.
GRANT ALL ON Boat TO Manager;
This command will give the role of Manager the right to carry out any operation on the table Boat.
Revoke
REVOKE ALL ON Boat FROM Admin;
– this command will take away any access rights from the role of Admin on the table Boat.
REVOKE DELETE ON Boat FROM Manager;
– this command will take away the right to delete data from the Boat table by the Manager.
De-Normalisation
Normalising our data model means we will have the minimum amount of redundancy.
If we are running a query that joins tables, this will be slower than running a query against a single table or view. This can have an effect on performance.
Denormalisation can be done by including an attribute in a table that should not be there according to the rules of normalisation.
Improving Performance with the Use of Views
View of selected rows or columns of these tables
Table 1
Table 2
Table 3
Query
View
A view is a virtual table which completely acts as a real table.
The use of view as a way to improve performance.
Views can be used to combine tables, so that instead of joining tables in a query, the query will just access the view and thus be quicker.
View
We can perform different SQL queries.
ANY QUESTIONS?
End of Topic - 11
References
http://stackoverflow.com/questions/7605707/clustered-vs-non-clustered