Itgs 2.2.2 Databases And Spreadsheets

Front 1

Database management system

Back 1

Database Management System
-software used to manage, manipulate, organise and interrogate structured data which is organised in many files/tables

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DBMS

Back 2

Database Management System

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a Database Management System provides.......

Back 3

-data independence
-access controls
-security (encryption)
-reports

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cell reference

Back 4

the address of a cell eg b3

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cell range

Back 5

a series of concurrent cells in a spreadsheet that are described by the putting the top left and the bottom right cell references separated by a colon e.g. B10:C22 would be the cell range that covered all of the cells from b10 to c22 inclusive

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relative reference

Back 6

a cell reference in a formula which when the formula is copied to a different cell, changes the formula to include a reference to a different cell which has the same spacial relationship to the formula as the original. eg copying formula a1*3 from d1 to d2 would change the formula to a2*3 automatically

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absolute reference

Back 7

a cell reference in a formula which when the formula is copied to a different cell, still points to the original cell reference - usually marked by $ signs. e.g. eg copying formula $a$1*3 from d1 to d2 would result in the formula in both being $a$1*3

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formula

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a step by step process for calculating a number on a spreadsheet typed in by the user - it automatically updates itself if the contents of the cells it refers to changes

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function

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predefined calculation that is inbuilt into spreadsheet software such as sum or average

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relational database

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a database that uses a series of tables to hold data about each entitiy

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entity

Back 11

an object, thing or person about which data is held in a database

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a query

Back 12

a database object that is used to interrogate the data - ie get information out of the data

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a form

Back 13

an interface part of the database that is used both for input of data and output of information to the user - can be used to enter data into a table or display the results of a sort or search (query!)

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gui in a database

Back 14

graphical user interface - the buttons, boxes and user friendly menus that are used to help the users navigate the database forms - moving through records, running reports and queries

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a search/ query,selects

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records that meet the criteria set in one or more fields

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a field

Back 16

a category of data collected about an entity(thing, person or event) eg first name

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a record

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a collection of fields about one entity (thing, person or event)

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report

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a printed output from a database that usually displays the results of a query, but occasionally will display the sorted contents of a table

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macro

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an automated procedure often programmed/recorded by the user, that performs a series of commonly used steps in a piece of sofware. Eg printing a particular sheet with the current data, running a query and exporting the data or copying data from one file to another

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SQL

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Structured query language

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Structured query language

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- the most widely used language for managing data in relational databases. It has been standardised and DBMS vendors now certify their products as being compliant with this.

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spreadsheet model

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mathmatical modelling done using a spreadsheet - good example is using a spreadsheet to do a budget and then using the model to answer questions about how changing income or expenses changes overall outcome

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flat file database

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type of database that only uses one table - fine if only one entity but can lead to problems if data is held about more than one entity(see problems card)

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problems of a flat file database

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data redundancy
time to input
storage space needed is greater
time to search data longer

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data redundancy

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unnecessary duplication of data in a database - data entered in more than one place leads to innaccuracy - one entry gets updated while another doesn't, slower searching, larger size and slower entry - avoided by using a relational database

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relational database

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each table only stores data about one entity. data is only entered once in its own table - no duplication

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primary key/key field

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the unique identifier that belongs to just one record in a table - eg student number

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foreign key

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where a primary keyof one entity appears in a table of a different entity to create a relationship between them eg student and class - it can appear multiple times as a foreign key but only once in the table where it is a primary key

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relationship

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the linking of two tables so that a search can access and link data from two related but different entities eg a search for a library book could show up recent loans history (which would be stored in the loans table not the book table)

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mail merge

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the use of data from a database query or spreadsheet list to create personalised documents or email

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form letter

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the starting point for a mail merge where all the items common to all the end products are added apart from the data that will change with each.

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steps in a mailmerge

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1)create a database query to select the required data
2)create a form letter (or certificate or brochure or email etc)
3) add the field names from the query (possibly using a wizard)
4) preview and confirm
5) merge the two together to produce a new document (the others don't change) with one letter/product for each record in the database
6) print and send!

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paper files

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never crash /difficult to hack/ durable
but can burn, get lost, need cross referencing (hard for more than 2 fields), difficult to transfer/share/update -

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data integrity

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how closely the data reflects reality - was it accurately entered? has it been kept up to date? is it consistent (the same in all parts of the system - often a problem with data redundancy)

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data consistency

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the sameness of the data across a system - does the system give different departments the same set of contact details for an employee? if not, there is a problem with data consistency

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data independence

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the separation of the data from the software used to manage it - with independence the data can be kept even if the software is upgraded

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exporting data

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the transfer of data from a database directly from a table or via a query into a form that can be imported into a spreadsheet - or vica versa

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CSV

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comma separated variable - a file format in which data appears as text separated by commas and returns - it can easily imported into a spreadsheet where each chunk of text goes into a cell OR
it can be easily imported into a database where each chunk gets put in a selected field and a return is a new record

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criteria

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a condition applied to a field (or fields) which is used to select a set of records

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boolean operators

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ways of combining criteria together - AND, OR and NOT

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AND

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records must meet both (or all if there are more than 2) criteria to be selected

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OR

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records must meet at least one of the criteria to be selected

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NOT

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this excludes some records from the search even if they meet the other criteria e.g. all names beginning with A AND B but NOT Bob or Alice

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data mining

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discovery and extraction of hidden predictive information from large databases - used by organisations such as financial institutions or supermarkets to target products or to understand their customers bettter

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data matching

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the extaction of information from the combination of data from two different databases using a common key eg passport number, social security number, date of birth combined with address. Allows for matching of police records with education records for eg

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data scrubbing

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the processing of going through a database and getting rid of records that contain errors - improves data integrity and makes the data more valuable

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data warehouse

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an integrated collection of data stored in one location belonging to one organisation

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data warehousing

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ftware,software used to create and maintain huge databases

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database

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a collection of data stored in an organised form that can be interrogated to produce information

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validation

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that act of checking that data which is being input is reasonable - it is a software function that works automatically on data input once the system is given the rules (see types card)

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types of validation

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range check (eg 1 to 100)
length check(eg postcode has 6 characters)
format check (eg has only letters)
presence check( is the field filled in)
check digit (see other card)

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database file

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a collection of records

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sort

Back 53

orders the set of records (or subset of records) according to numerical or alphabetical order in the selected field(s)