Databases Cheyenne Ortega

Databases  A database is a collection of related data, stored in an organized manner so that it can be retrieved later.  Databases are used in many different areas, an many IT systems have databases ‘behind the scene’, even if they are not immediately obvious.  A database is a collection of related data, stored in an organized manner so that it can be retrieved later.  Databases are used in many different areas, an many IT systems have databases ‘behind the scene’, even if they are not immediately obvious.

Examples of Databases  Business DB’s: includes customer information, product data, and supplier details. They are used by E-Commerce businesses such as Amazon, maintaining not just records of products but also shopping behaviors of the customers, allowing them to customize each costumers shopping experience.  Transport DB’s: flight or train information, providing passenger information and allowing customers to view and book destinations from anywhere as long as they have access to the internet.  Search engines: Google, Yahoo, and Bing use DB’s to store contents of web pages, and details about the user’s behaviors, including common search engines and trending topics.  Business DB’s: includes customer information, product data, and supplier details. They are used by E-Commerce businesses such as Amazon, maintaining not just records of products but also shopping behaviors of the customers, allowing them to customize each costumers shopping experience.  Transport DB’s: flight or train information, providing passenger information and allowing customers to view and book destinations from anywhere as long as they have access to the internet.  Search engines: Google, Yahoo, and Bing use DB’s to store contents of web pages, and details about the user’s behaviors, including common search engines and trending topics.

Examples of Databases  Social networks: Myspace, Facebook, Instagram and Twitter use a similar approach as the search engines.  Online DB’s: the freer encyclopedia Wikipedia, holds huge volumes of articles, images, and video accessible to anybody with an internet connection.  Government DB’s: include criminal records, tax records, medical records, library books, schools DB’s of students. All are linked together which makes privacy and control of data and ethical and social issue  Social networks: Myspace, Facebook, Instagram and Twitter use a similar approach as the search engines.  Online DB’s: the freer encyclopedia Wikipedia, holds huge volumes of articles, images, and video accessible to anybody with an internet connection.  Government DB’s: include criminal records, tax records, medical records, library books, schools DB’s of students. All are linked together which makes privacy and control of data and ethical and social issue

Software used  The software used to create and maintain databases is known as DATABASE MANAGEMENT SYSTEM or RELATIONAL DATABASE MANAGEMENT SYSTEM.  Examples of DBMS software with various capabilities include Microsoft access, MySQL, Microsoft SQL serve, and FileMaker Pro.  Spreadsheet application focus on numerical calculation and are not considered database programs.  The software used to create and maintain databases is known as DATABASE MANAGEMENT SYSTEM or RELATIONAL DATABASE MANAGEMENT SYSTEM.  Examples of DBMS software with various capabilities include Microsoft access, MySQL, Microsoft SQL serve, and FileMaker Pro.  Spreadsheet application focus on numerical calculation and are not considered database programs.

Database structure  Databases organize information into fields, records, and tables, determined by how the pieces of data relate to each other.  Fields are the smallest pieces of information in a database.  Fields are the names of a student price of a product, and the cell phone number of an employee. There are the property of an item.  Record is a collection of fields that relate to the same item.  The name, class, grade, home address, and address for one student form a record for that student.  Tables are collections of records that are all of the same type.  All records which represent students would go in the Student table.  Databases organize information into fields, records, and tables, determined by how the pieces of data relate to each other.  Fields are the smallest pieces of information in a database.  Fields are the names of a student price of a product, and the cell phone number of an employee. There are the property of an item.  Record is a collection of fields that relate to the same item.  The name, class, grade, home address, and address for one student form a record for that student.  Tables are collections of records that are all of the same type.  All records which represent students would go in the Student table.

Database structure  Primary key is a field which is different for every record in that table. This allows each record to be uniquely identified.  A student ID number would make an appropriate primary key, assuming each student has a different number.  Student name or phone number would not be a good primary key because several students might have the same name or same number.  Composite key consists of two or more fields which separately do not uniquely identify records, but do when combined.  Primary key is a field which is different for every record in that table. This allows each record to be uniquely identified.  A student ID number would make an appropriate primary key, assuming each student has a different number.  Student name or phone number would not be a good primary key because several students might have the same name or same number.  Composite key consists of two or more fields which separately do not uniquely identify records, but do when combined.

Database structure  Secondary keys (alternative keys or indexes) are a field which might frequently be used to search a table.  Data type is what each field in a database must have. It determines2 what sort of date can be stored in it, such as text, numbers, date, or an image.  Data types are a good first step to help ensure validation of data by only allowing data of the desired type.  Secondary keys (alternative keys or indexes) are a field which might frequently be used to search a table.  Data type is what each field in a database must have. It determines2 what sort of date can be stored in it, such as text, numbers, date, or an image.  Data types are a good first step to help ensure validation of data by only allowing data of the desired type.

Flat file databases  A flat file database is a database which contains just one table.  Redundant data: data that is needlessly repeated.  Redundant data causes several problems:  Data integrity- the more often that data is repeated the higher the chance that a mistake will be made. This leads to different, inconsistent, values in different records.  Data integrity- relating to the above, if the repetition occurs then the whole database must be searched for this mistake of data. This creates problems because some copies of the field might be updated while others are missed, creating consistent data.  Wasted storage space- multiplied by thousands or even hundreds of thousands records, redundant data can consume a lot of disk and memory space.  A flat file database is a database which contains just one table.  Redundant data: data that is needlessly repeated.  Redundant data causes several problems:  Data integrity- the more often that data is repeated the higher the chance that a mistake will be made. This leads to different, inconsistent, values in different records.  Data integrity- relating to the above, if the repetition occurs then the whole database must be searched for this mistake of data. This creates problems because some copies of the field might be updated while others are missed, creating consistent data.  Wasted storage space- multiplied by thousands or even hundreds of thousands records, redundant data can consume a lot of disk and memory space.

Normalization and Relation databases  A beter way to represent is using a relational data. Relational databases split data into multiple tables, each containing records related to one type of item.  The process of creating a relational database which has no redundant data is known as normalization.  A beter way to represent is using a relational data. Relational databases split data into multiple tables, each containing records related to one type of item.  The process of creating a relational database which has no redundant data is known as normalization.

Relationships  Once the data has been normalized into separate tables, those tables must be linked, or related to other tables.  When looking at a book we need a way to find out the information about the author.  There is a one-to-many relationships here: one author has many books, but one book only has one author.  The AuthorID field in the books table is known as a foreign key, because it only exists to be part of a relationship with another table.  Once the data has been normalized into separate tables, those tables must be linked, or related to other tables.  When looking at a book we need a way to find out the information about the author.  There is a one-to-many relationships here: one author has many books, but one book only has one author.  The AuthorID field in the books table is known as a foreign key, because it only exists to be part of a relationship with another table.

Queries  A query is a way of selecting only the records in a database that match certain criteria. For example:  All students who achieved over 90% in the test.  All results from Student A which were less than 40%  All products that have less than 10 items in stock  All customers whose last purchase was over 6 months ago  All appointments today between 9:00 and 12:00  All books which are paperback and which longer than 400 pages  All books by American or English  A query is a way of selecting only the records in a database that match certain criteria. For example:  All students who achieved over 90% in the test.  All results from Student A which were less than 40%  All products that have less than 10 items in stock  All customers whose last purchase was over 6 months ago  All appointments today between 9:00 and 12:00  All books which are paperback and which longer than 400 pages  All books by American or English

Queries  Boolean operators such as AND, OR, and NOT are used to combine criteria. For example:  Language is English OR Spanish  Language is NOT English  Language is Italian AND author is Levi  The words AND, OR, and NOT are mathematical operators.  Parameter query prompts the user for a value when the query is run.  Parameter queries allow criteria to be specified at run-time rather design-time, allowing much greater flexibility.  Boolean operators such as AND, OR, and NOT are used to combine criteria. For example:  Language is English OR Spanish  Language is NOT English  Language is Italian AND author is Levi  The words AND, OR, and NOT are mathematical operators.  Parameter query prompts the user for a value when the query is run.  Parameter queries allow criteria to be specified at run-time rather design-time, allowing much greater flexibility.

Forms  Forms are used to present a user friendly graphical interface for entering and altering data in a database.  Forms are used to present a user friendly graphical interface for entering and altering data in a database.

Reports  Reports are a way of presenting data from table in a database in a more professional manner than the default data sheet view.  Like forms, reports can be customized in terms of layouts, colors, company logos, and data field layout.  Reports are a way of presenting data from table in a database in a more professional manner than the default data sheet view.  Like forms, reports can be customized in terms of layouts, colors, company logos, and data field layout.

Validation  Data validation : is the process of ensuring that data is in the correct format for a particular field.  For example, validation could be used to ensure that when a credit card number is entered, it contains exactly seventeen numbers, and no letters.  Data validation : is the process of ensuring that data is in the correct format for a particular field.  For example, validation could be used to ensure that when a credit card number is entered, it contains exactly seventeen numbers, and no letters.

Data matching  Data matching (A.K.A. Computer matching) is often used to build up a profile of an individual by combining data about them from several databases.  Commonly used by governments to root out fraud, such as false benefit claim.  For example, in the UK adults living on their own, or living with non tax payers such as children or students, qualify for a lower council tax rate.  Data matching (A.K.A. Computer matching) is often used to build up a profile of an individual by combining data about them from several databases.  Commonly used by governments to root out fraud, such as false benefit claim.  For example, in the UK adults living on their own, or living with non tax payers such as children or students, qualify for a lower council tax rate.

Data mining in business  Data mining (A.K.A. knowledge discovery) is the process of discovering hidden patterns and trends in large database.  These patterns and trends would be difficult or impossible for a human to spot, in part because of the large volume of data.  Data mining (A.K.A. knowledge discovery) is the process of discovering hidden patterns and trends in large database.  These patterns and trends would be difficult or impossible for a human to spot, in part because of the large volume of data.

Data mining in health  Health insurance companies perform a similar task when a person applies for medical insurance, medical histories and family histories are checked to determine an individual's risk.

Data Protection Act  The DPA is a UK law that governs the use of data collected and stored on a computer system.  The DPA identifies different stakeholders including data users, data subject, data controllers, and information commissioner.  The DPA obliges data users to follow rules when collecting, storing, and processing data.  The DPA is a UK law that governs the use of data collected and stored on a computer system.  The DPA identifies different stakeholders including data users, data subject, data controllers, and information commissioner.  The DPA obliges data users to follow rules when collecting, storing, and processing data.