Normalisation & RDBMS

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Normalisation & RDBMS - it can be downloaded from http://www.teach-ict.com/contributors/Ritchie_King.htm

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Presentation Transcript

Database Systems : 

Database Systems A guide to producing a fully functional RDBMS

How Can this Presentation Help Me? : 

How Can this Presentation Help Me? If you work through this presentation use the terminology quoted and produce all the diagrams and documentation mentioned throughout this presentation, you will have succeeded in meeting most of the requirements necessary to produce a successful report on the analysis, design and implementation of a Relational Database. Do not move on from one section to the next until you fully understand and can apply the concepts described in this presentation

Slide 3: 

Contents Theory and terminology The Analysis Phase Requirements Definition Functional Dependency & Relationships Normalisation Entity Relationship Diagrams Data Dictionaries & Data Types Functions [Input, Processes & Outputs] The Design Phase The Implementation Phase

Slide 4: 

Data – A collection of raw facts and figures Information – Final product created from the raw data after processing Database – A collection of related information organised in a structured way to allow easy retrieval of any one item Some Terminology

Slide 5: 

Table – A complete set of data. Also known as an entity or relation Record – One row of the table Field – One column of the table. Also known as an attribute Elements of a database Types of Database Flat file Database – Single table Relational Database – Multi table

Slide 6: 

Flat-file Database – Single table A telephone directory is an example of a flat file database Problems with flat-file databases Redundant Data Data is repeated and hence stored many times. This wastes disk space and slows down query time. Typographical Errors Greater likelihood of errors when data is being entered.

Slide 7: 

Problems with flat-file databases Updating Data Every occurrence of a piece of data will have to be updated if its value changes Modifying Data If a record is deleted this may destroy all reference to a particular piece of data To overcome these problems it is better to store data in multiple tables i.e. a Relational database

Slide 8: 

Characteristics of a relational database Data is stored in a set of tables Tables are joined by relational links Reduces duplication of data in database - Normalisation Allows greater flexibility and efficiency

Slide 9: 

Relational Database – Multi table The data is stored in multiple tables. This is the most common way of keeping a computerised database Each table must have a unique reference for each record which is called the Primary key Replicating these into other tables creates the Foreign key These foreign keys form the Relationships that link the tables together

Slide 10: 

Relational Database – Multi table Redundant Data The disk space required to store data is reduced and queries can be performed more quickly. Typographical Errors As data is only entered once the chances of these errors occurring are greatly reduced..

Slide 11: 

Relational Database – Multi table Updating Data Data need only be updated once as it would only have been entered once Modifying Data Problems of the kind mentioned earlier disappear. New records will simply have their attributes added to the relevant table

Slide 12: 

Database Management System [DBMS] DBMS A computer program or collection of computer programs that provides the necessary tools to create and manipulate the data in a database RDBMS Relational Database Management Systems are used to create and manipulate relational databases e.g. Microsoft Access Oracle Lotus Approach

Slide 13: 

Database Systems - Construct a data model of an existing, non computerised system THE ANALYSIS PHASE

Database Systems : 

Database Systems Analysis Phase Requirements Definition Normalisation Entity-Relationship Diagrams Data Dictionaries Functions

Database Systems : 

Database Systems Analysis Requirements Definition Normalisation Entity-Relationship Diagrams Data Dictionaries Functions

Requirements Definition : 

Requirements Definition When we normalise any type of database system we need to know what the data in the system means. Therefore we either have to talk to the people who use the existing system or we have to be supplied with very detailed information about how the system works and the data stored within it. The following slide shows an example of some current data. Below this are listed some questions that help establish the requirements of the new system. Can you think of anything else the analyst might ask?

Requirements Definition : 

Requirements Definition Does each salesperson have their own sales area? Does each customer deal with only one salesperson ? Does each customer only receive goods from one warehouse? The answer to these questions will influence how we structure the database system. The answer to these questions and others make up the Requirements Definition

Database Systems : 

Database Systems Analysis Requirements Definition Normalisation Entity-Relationship Diagrams Data Dictionaries Functions

Functional Dependency : 

Functional Dependency Functional dependency means that there must be only a one-to-one dependency for each attribute mapped from a primary key to that attribute. For example, the engine number of a car [Primary Key] can only have engine capacity as an attribute of that key creating Functional Dependency BUT A particular engine capacity can be associated with the engine numbers of many makes of car. This does not give rise to Functional Dependency It defines a relationship in which the existence of one entity/attribute is entirely dependent on the existence of another (one-to-one).

Functional Dependency - Practical Example : 

Functional Dependency - Practical Example Order Number is the primary key. The value for each attribute of SALES, except Item Price, depends upon the value of the primary key. All attributes of SALES, except Item Price, are Functionally Dependent on the primary key Item Price is Functionally Dependent on the the attribute Item

Slide 21: 

Relationships Having established a definition for the term Functional Dependency we now need to explore the different types of relationships that can exist between attributes in different entities: There are 3 types of relationships that can exist: One to One Relationships One to Many Relationships Many to Many Relationships Now lets take a closer look at each of these on the next slides

Entity Relationships : 

Entity Relationships One-to-one A blind person owns a guide dog which is exclusively theirs.

Entity Relationships : 

Entity Relationships One-to-many A doctor may have many patients, but a patient is assigned to only one doctor.

Entity Relationships : 

Entity Relationships Many-to-many A film may have many stars and each star may act in many films.

Slide 25: 

Important Note: An RDBMS system cannot produce a robust solution if two or more of the entities have a many to many relationship To overcome this problem it is necessary to introduce another entity thus creating One to Many relationships between itself and the offending entities This can become a common occurrence when you are working with larger and more complex database systems

Slide 26: 

Now you should have the tools and understanding you require in order to normalise the data in order that a solution can be produced using an RDBMS [Relational Database Management System] Please take your time when working through the next part of this presentation and revisit it again and again until you are completely comfortable with the concepts involved Normalisation of the data is perhaps the single most important aspect of developing a robust solution to any database problem!

Normalisation : 

Normalisation Normalisation is a 'fancy' term for a set of rules, designed to make sure that a database is organised in the best way possible This allows the data to be processed more efficiently and any query to be processed. These rules depend on relationships being established between the entities to create a functional dependency between them.

The normalisation process involves: : 

The normalisation process involves: Finding and grouping together all the entities and their attributes. Removing repeating groups of data. This is another way of saying that there is no point in storing a persons' name and details etc. in many different places within a database. Providing unique keys for each entity in the database system. You need to have a way of making sure that when you delete 'Paul Smith' from the Transactions entity that it is the correct person.

The Three Major Stages of Normalisation: : 

The Three Major Stages of Normalisation: First Normal Form 1NF is the first level of normalisation. An entity (table) is in First Normal form if it contains no repeating attributes (fields) or groups of attributes. Second Normal Form An entity is in 2NF if no attribute (not part of the primary key) is dependent on only part of the primary key. This only applies to entities with concatenated primary keys. Third Normal Form An entity is in 3NF if all attributes are entirely dependent on the primary key and not on any attribute that is not part of the primary key.

To produce a set of entities in First Normal Form (1NF): : 

To produce a set of entities in First Normal Form (1NF): Remove repeating (multiple) groups within the primary entities (tables) so that each record (row) within the entity is the same length. Repeating groups then become new entities, linked together by a one-to-many relationship. Relationships are created by including a primary key from one entity as a foreign key in another entity

Charlie’s Baker Shop : 

Charlie’s Baker Shop

Charlie’s Baker Shop : 

Charlie’s Baker Shop

Charlie’s Baker Shop : 

Charlie’s Baker Shop Items Purchased Orders

Charlie’s Baker Shop : 

Charlie’s Baker Shop Items Purchased Orders

Charlie’s Baker Shop : 

Charlie’s Baker Shop Order No. can be used to uniquely identify each record and can therefore be made the primary key. Orders (Order No. Acc. No. Customer Address Date Total Cost) Orders Table:

Charlie’s Baker Shop : 

Charlie’s Baker Shop Items Purchased Table: No one attribute can be used to uniquely identify a record. Order No. and Item together can uniquely identify a record. Concatenated key is required Items (*Order No. Purchased Item Quantity Item Price)

Charlie’s Baker ShopFirst Normal Form : 

Charlie’s Baker ShopFirst Normal Form Items (*Order No. Purchased Item Quantity Item Price Orders (Order No. Acc. No. Customer Address Date Total Cost)

The Three Major Stages of Normalisation: : 

The Three Major Stages of Normalisation: First Normal Form 1NF is the first level of normalisation. An entity (table) is in First Normal form if it contains no repeating attributes (fields) or groups of attributes. Second Normal Form An entity is in 2NF if no attribute (not part of the primary key) is dependent on only part of the primary key. This only applies to entries with concatenated primary keys. Third Normal Form An entity is in 3NF if all attributes are entirely dependent on the primary key and not on any attribute that is not part of the primary key.

To produce a set of entities in Second Normal Form (2NF): : 

To produce a set of entities in Second Normal Form (2NF): Test for dependency by testing each particular attribute in turn to check that it can be uniquely identified by making use of all the primary key. This test need not be completed unless you have at least one table which requires a concatenated Primary Key Remove all partially dependent attributes to a new entity. N.B. – A concatenated key occurs when you need two fields together in order to uniquely identify a record

Charlie’s Baker ShopFirst Normal Form : 

Charlie’s Baker ShopFirst Normal Form Items (*Order No. Purchased Item Quantity Item Price) Orders (Order No. Acc. No. Customer Address Date Total Cost)

Charlie’s Baker Shop : 

Charlie’s Baker Shop Because this entity has a single attribute as the primary key there can be no partial dependencies and therefore the entity is already in 2NF. Orders Table:

Charlie’s Baker Shop(2NF Step 1) : 

Charlie’s Baker Shop(2NF Step 1) Items Purchased Table: Primary key is Order No. and Item Test for dependency by testing each particular attribute.

Charlie’s Baker Shop(2NF Step 1) : 

Order No Quantity YES Item Quantity is functionally dependent on Order No. and Item. Charlie’s Baker Shop(2NF Step 1) Items Purchased Table: Primary key is Order No. and Item Test for dependency by testing each particular attribute.

Charlie’s Baker Shop(2NF Step 1) : 

Order No Item Price NO Item Item price is functionally dependent Item, but not on Order No. and Item Order No Quantity YES Item Quantity is functionally dependent on Order No. and Item. Charlie’s Baker Shop(2NF Step 1) Items Purchased Table: Primary key is Order No. and Item Test for dependency by testing each particular attribute.

Charlie’s Baker Shop(2NF Step 2) : 

Charlie’s Baker Shop(2NF Step 2) Remove any partially dependent attributes to a new entity

Charlie’s Baker Shop(2NF Step 2) : 

Charlie’s Baker Shop(2NF Step 2) Part Order Price List Remove any partially dependent attributes to a new entity

Charlie’s Baker Shop(2NF Step 2) : 

Charlie’s Baker Shop(2NF Step 2) Part Order Create a relationship between the tables Price List

Charlie’s Baker ShopSecond Normal Form : 

Charlie’s Baker ShopSecond Normal Form Price List (Item Item Price) Orders (Order No. Acc. No. Customer Address Date Total Cost) Part Order (*Order No. *Item Quantity)

The Three Major Stages of Normalisation: : 

The Three Major Stages of Normalisation: First Normal Form 1NF is the first level of normalisation. An entity (table) is in First Normal form if it contains no repeating attributes (fields) or groups of attributes. Second Normal Form An entity is in 2NF if no attribute (not part of the primary key) is dependent on only part of the primary key. This only applies to entries with concatenated primary keys. Third Normal Form An entity is in 3NF if all attributes are entirely dependent on the primary key and not on any attribute that is not part of the primary key.

To produce a set of entities in Third Normal Form (3NF): : 

To produce a set of entities in Third Normal Form (3NF): Test each attribute in turn to check for dependency on the primary key. Remove all transitive dependencies to a new entity. A transitive dependency is where an attribute is dependent on another attribute (or attributes) that is (are) NOT the primary key

Charlie’s Baker ShopSecond Normal Form : 

Charlie’s Baker ShopSecond Normal Form Price List (Item Item Price) Orders (Order No. Acc. No. Customer Address Date Total Cost) Part Order (*Order No. *Item Quantity)

Charlie’s Baker Shop - 3NF Step1 : 

Charlie’s Baker Shop - 3NF Step1 Test for dependency

Charlie’s Baker Shop - 3NF Step1 : 

Charlie’s Baker Shop - 3NF Step1 Test for dependency

Charlie’s Baker Shop - 3NF Step1 : 

Charlie’s Baker Shop - 3NF Step1 Test for dependency

Charlie’s Baker Shop - 3NF Step1 : 

Charlie’s Baker Shop - 3NF Step1 Test for dependency

Charlie’s Baker Shop - 3NF Step1 : 

Charlie’s Baker Shop - 3NF Step1 Test for dependency

Charlie’s Baker Shop - 3NF Step1 : 

Charlie’s Baker Shop - 3NF Step1 Test for dependency

Charlie’s Baker Shop - 3NF Step2 : 

Charlie’s Baker Shop - 3NF Step2 Remove transitive dependencies to a new entity

Charlie’s Baker Shop - 3NF Step2 : 

Charlie’s Baker Shop - 3NF Step2 Orders Customers Remove transitive dependencies to a new entity

Charlie’s Baker Shop - 3NF Step2 : 

Charlie’s Baker Shop - 3NF Step2 Create a relationship between the tables Orders Customers

Charlie’s Baker ShopThird Normal Form : 

Charlie’s Baker ShopThird Normal Form Normalisation Complete Orders (Order No. *Acc. No. Date Total Cost) Price List (Item Item Price) Part Order (*Order No. *Item Quantity) Customers (Acc. No. Customer Address)

Slide 62: 

Normalisation - 1. Remove repeating groups to create a new entity 2. Create a relationship using one of the attributes that are left [Usually the primary key] The Six Point Plan 3.‘Check out’ entities with concatenated keys. If any attribute is not fully dependent on both parts of the primary key remove it to create a new entity. 4. Create a relationship using one of the attributes that are left [Usually the primary key] 5.‘Check out’ every entity. If any attribute is dependent on any attribute other than the primary key, remove it into a new entity. 6. Create a relationship using one of the attributes

Database Systems : 

Database Systems Analysis Requirements Definition Normalisation Entity-Relationship Diagrams Data Dictionaries Functions

Entity - Relationship Diagrams : 

Entity - Relationship Diagrams E-R diagrams show the structure of the data to be modelled. They are a convenient method for representing the relationships, entities and attributes in a system. This is done by illustrating a system with a diagram to produce a detailed specification for each entity and the attributes within them.

Symbols used in an E – R diagram : 

Symbols used in an E – R diagram Entity – a collection of data [table] Attribute – a data item in an entity [field] ENTITY

Symbols used in an E – R diagram : 

Symbols used in an E – R diagram Relationship – a description of the link between two entities. Key Attribute – a data item which makes up the primary key or part of it.

Slide 67: 

Simple Examples 1. A blind person owns a guide dog 2. A doctor treats many patients

Slide 68: 

Simple Examples 3. A film may have many stars and each star may be in many films.

Charlie’s Baker ShopThird Normal Form : 

Charlie’s Baker ShopThird Normal Form Orders (Order No. *Acc. No. Date Total Cost) Price List (Item Item Price) Part Order (*Order No. *Item Quantity) Customers (Acc. No. Customer Address)

Slide 70: 

Charlie’s Baker Shop Determine the relationships between the entities.

Charlie’s Baker ShopThird Normal Form : 

Charlie’s Baker ShopThird Normal Form Orders (Order No. *Acc. No. Date Total Cost) Price List (Item Item Price) Part Order (*Order No. *Item Quantity) Customers (Acc. No. Customer Address)

Slide 72: 

List the attributes alongside each entity Charlie’s Baker Shop

Database Systems : 

Database Systems Analysis Requirements Definition Normalisation Entity-Relationship Diagrams Data Dictionaries Functions

Slide 74: 

Data Dictionary A data dictionary is a database about a database and is often called metadata [data about data] It is created at the analysis stage to provide a record of the attributes and their properties: Data type Required [or not] I.e. Can this field be left blank ? Range Format When the database is up and running it acts as a useful reference

Slide 75: 

Data Types Text A text attribute only stores letters from the standard 26 character alphabet Number Used to hold numeric data. Remember to show the range of numbers to be stored [ Use common sense] Text and Number Used for alphanumeric data e.g. An address that may contain a house number and street name.

Slide 76: 

Data Types Date Dates can be laid out using various formats. Two common formats are short (dd/mm/yy) or (dd/mm/yyyy) and long (month day, year) Time Various formats can be used here. A time of day, a duration, 24-Hr clock, am/pm etc. Boolean These are binary values only having two states. True/false, yes/no or off/on.

Slide 77: 

Data Types The data types and formats used at this stage will be general and will be mapped on to those available in the RDBMS [Relational Database Management System] in the design phase.

Slide 78: 

Data Dictionary for Charlie’s Baker Shop

Database Systems : 

Database Systems Analysis Requirements Definition Normalisation Entity-Relationship Diagrams Data Dictionaries Functions

Slide 80: 

Functions A function is anything that acts on the data in a database system and is classified as input, process or output. Input An input is a function that places new data in the system such as creating, updating or deleting data Process An automated function within the database system e.g. automatic update of an attribute, checking the particular value of an attribute, changing or calculating new values from the data

Slide 81: 

Functions Output A function that produces data from the database system e.g. a report, letter or summary of the data Beyond these Operational functions modern computerised database systems can provide a wide range of Strategic and Tactical information which can assist with planning and organising e.g. queries and ordered lists can provide the Company with invaluable marketing information

Slide 82: 

Listed Functions that affect each entity of the Charlie’s Baker Shop database

Slide 83: 

Database Systems - Design database structures to represent the data model THE DESIGN PHASE

Slide 84: 

Database Systems-Design Phase Database Structure and item names relate to the data model Unique keys are chosen for all Database structures Validity checks represent the data model Data item characteristics represent the data model Designed structures are appropriate to the intended implementation method

Slide 85: 

Database Systems-Design Phase Database Structure and item names relate to the data model Unique keys are chosen for all Database structures Validity checks represent the data model Data item characteristics represent the data model Designed structures are appropriate to the intended implementation method

Slide 86: 

The conceptual design [Data Model or E- R Diagram] has already been created in the analysis phase using Entities, Relationships and Attributes The entities now become tables and the relationships between these entities are preserved between the tables Most RDBMS have syntactical rules that govern how fields and tables are named. This may affect how we construct the field and table names.

Slide 87: 

Database Systems-Design Phase Database Structure and item names relate to the data model Unique keys are chosen for all Database structures Validity checks represent the data model Data item characteristics represent the data model Designed structures are appropriate to the intended implementation method

Slide 88: 

Indexes The keys chosen for the database structures are the same as those identified in the data model. These remember were established during the normalisation process Some RDBMS include tools that create indexes of fields to speed up searches within the database. However, only Primary and Foreign keys should normally be indexed to help speed up this process.

Slide 89: 

Database Systems-Design Phase Database Structure and item names relate to the data model Unique keys are chosen for all Database structures Validity checks represent the data model Data item characteristics represent the data model Designed structures are appropriate to the intended implementation method

Slide 90: 

Data entered into the database should be valid and correct. Most RDBMS contain tools which will offer 3 types of validity check PRESENCE Checks to see if a value is present or not. E.g. if a field value must be set, a presence check would be carried out on it. RANGE Checks to see if a value entered is within a prescribed range. RESTRICTED CHOICE This would ensure that the user only entered data that corresponded to a list of pre-set values e.g. N S E or W

Slide 91: 

Database Systems-Design Phase Database Structure and item names relate to the data model Unique keys are chosen for all Database structures Validity checks represent the data model Data item characteristics represent the data model Designed structures are appropriate to the intended implementation method

Slide 92: 

Every RDBMS has its own set of data types that it can implement. In the design phase we create a more detailed data dictionary that identifies the field types, sizes, keys and validity checks that can be implemented in the RDBMS

Slide 93: 

Database : Charlie’s Baker Shop Table : Orders

Slide 94: 

Database Systems-Design Phase Database Structure and item names relate to the data model Unique keys are chosen for all Database structures Validity checks represent the data model Data item characteristics represent the data model Designed structures are appropriate to the intended implementation method

Slide 95: 

State the relationships that will be implemented using the RDBMS. These should be the same as for the E-R diagram. However, in the design phase we show the relationships between the primary and foreign key fields in each table. Relationships

Slide 96: 

Charlie’s Baker Shop [Customers.Acc.No.] 1: M [Orders.Acc.No.] Price List (Item Item Price) Part Order (*Order No. *Item Quantity) [Orders.Order No] 1: M [Part Order.Order No] [Price List.Item] 1: M [Part Order.Item]

Slide 97: 

When you are designing the database structures for your implementation you must always consider what your RDBMS is capable of doing. There is no point designing a system that cannot be implemented with the software that you have available.

Slide 98: 

Database Systems - Implement a designed database structure based on an existing system THE IMPLEMENTATION PHASE

Slide 99: 

Correctly implement database structures from design Perform data manipulations effectively Carry out queries to meet given criteria efficiently Produce reports to meet given specifications Evaluate the database structure against the existing system Ensure data is well managed and secure

Slide 100: 

Database Systems Implementation Phase Correctly implement database structures from design Perform data manipulations effectively Carry out queries to meet given criteria efficiently Produce reports to meet given specifications Evaluate the database structure against the existing system Ensure data is well managed and secure

Slide 101: 

Using the chosen RDBMS each of the tables within your design including all the relevant fields will be specified and established. Implement all the features of your detailed data dictionary i.e. Table names Fieldnames and whether indexed or not Validity checks Primary/foreign keys Once and only once the structure has been established, is it possible to enter data into the tables

Slide 102: 

Database Systems Implementation Phase Correctly implement database structures from design Perform data manipulations effectively Carry out queries to meet given criteria efficiently Produce reports to meet given specifications Evaluate the database structure against the existing system Ensure data is well managed and secure

Slide 103: 

EDIT An edit manipulation involves the user changing data already present in the database   SORT A sort manipulation takes a range of data from the database and sorts it on the values in one or more fields   INSERT An insert manipulation involves the user adding new data to tables within the database   DELETE A delete manipulation involves the user removing data from tables within the database

Slide 104: 

Database Systems Implementation Phase Correctly implement database structures from design Perform data manipulations effectively Carry out queries to meet given criteria efficiently Produce reports to meet given specifications Evaluate the database structure against the existing system Ensure data is well managed and secure

Slide 105: 

Queries are questions you can ask of the data in tables within the database. They are similar to searches you would perform within a flat-file database Queries create subsets of the data within the database by field, record or both A query performed on a relational database will always produce a table A query can be performed on more than one table because the relationships between primary and foreign keys link the tables together Queries not only produce subsets of the data, but can be used to perform mathematical operations on this data Base Tables – The original table that the query acted upon Answer Tables – The table created by the query. This contains a subset of the data from the base table/s

Slide 106: 

Textual Queries that act on fields of the text data type   Numeric Queries that act on fields of the numeric data type   Exact Finds a specific match on a field for particular criteria e.g. customers with surname ‘Smith’.   Inexact Looks for values within a range in a particular field e.g. customers with names beginning with 'S'   Combinations of search criteria Uses a combination of criteria e.g. All customers who ordered items costing <£1.50 Styles of Query

Slide 107: 

Different tools have been developed to allow us to query a relational database through the RDBMS   Graphical Tools Allow us to select and enter the details for the query graphically e.g. The tool you are using in Microsoft Access   Structured Query Language [SQL] A recognised international standard for creating queries for relational databases e.g. SELECT DISTINCT [Orders].[Acc.No.], Sum([Orders].[Total Cost]) AS [SumOfTotal Cost] FROM [Orders] GROUP BY [Orders].[Acc.No.]; Often, an RDBMS will use both types of tool. Inexperienced users would use the graphical tool Experienced users would use SQL

Slide 108: 

Database Systems Implementation Phase Correctly implement database structures from design Perform data manipulations effectively Carry out queries to meet given criteria efficiently Produce reports to meet given specifications Evaluate the database structure against the existing system Ensure data is well managed and secure

Slide 109: 

A report is like a query in that it can summarise the data in the database. However reports are used to produce printed output [ Hard Copy] e.g. The user may require a listing of all customers and their addresses from the database Reports N.B. When producing reports using MS Access it is possible to perform some basic statistical analysis on the data if the data type is numeric

Slide 110: 

Database Systems Implementation Phase Correctly implement database structures from design Perform data manipulations effectively Carry out queries to meet given criteria efficiently Produce reports to meet given specifications Evaluate the database structure against the existing system Ensure data is well managed and secure

Slide 111: 

When the relational database has been produced an evaluation should be performed against the existing system to identify any improvements and a report compiled to include the following: Information summary of how the existing system is used outlining restrictions of this system and limited usage Improvements in the efficiency and effectiveness of the new system e.g. Reduction in entry and storage of duplicate data Automation of operations such as producing reports Saving in man hours for entering data and reduction in data entry errors New facilities available through the new system such as reports that analyse the data statistically or queries that automate the production of summary data

Slide 112: 

Database Systems Implementation Phase Correctly implement database structures from design Perform data manipulations effectively Carry out queries to meet given criteria efficiently Produce reports to meet given specifications Evaluate the database structure against the existing system Ensure data is well managed and secure

Slide 113: 

Legislation – Your legal responsibilities   Data Protection Act (1998)   Ensures that people who keep information on computer (Data Users) give rights to individuals (Data Subjects) who have information recorded about them on computer   Copyright, Design & Patents Act (1988)   Most published material is protected by this act i.e. there are restrictions to the use you can make of such material in respect of copying selling and adapting it.   Computer Misuse Act (1990)   This act provides regulations that govern the access to and use of computer systems and the information within them e.g. unauthorised use of another person's username and password.

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