ITGS - Data And Databases
- 2. What is Data?Data are “raw” facts23Red1.8All of the above are examples of data items When the data is put in a context it becomes information23 years old The colour is redThe height is 1.8m
- 3. Use of Data The storage and processing of data is one of the major uses of IT in the world.There are many types of programmesavailable that can process data but the two main types are:DatabasesSpreadsheetsThere are several different data types that can be stored and processed in these programes.
- 4. Data types in MS Access (a database)
- 5. Data types in MS Excel (a spreadsheet)
- 6. Logic/Boolean data typeThis type of data can have only two states.
- 7. Date data typeDates and Types have a special format
- 8. Numeric Data typesThere are several numeric data types that applications can use. Historically the reason that different data types were used in programmes was to save space.Integers are whole number that are both positive and negative i.e. 256, -123
- 9. Real numbers are the set of positive integers
- 10. Decimals are the numbers that have a fraction with them i.e. 2.56, 19.4Alpha Numeric Data typesThis data type contains both text and numbersThis is a very common data type and includes different number formats that are, strictly speaking, NOT numbers(09) 8383 456021-034-98309 238 765
- 11. OLE ObjectsOLE = Object Linking and EmbeddingThese can be a range of objects such as:SoundVideoImagesTextThis data type enables you to create objects in one application and linki.e. Create a photo of a product to place in an online catalog.
- 12. Why use databases?Databases can store very large numbers of records efficiently (they take up little space) It is very easy and quick to find information. It is easy to add new data and to edit or delete old data. Data can be searched easily (eg, 'find all Ford cars'). Data can be sorted easily, for example into 'date first registered' order.
- 13. Why use databases?Data can be taken into other applications, for example a mail-merge letter to a customer.More than one person can access the same database at the same time - multi-access. Security may be better than in paper files. Databases can be used to store information entered into web pages.Most interactive websites:Internet bankingOnline auctionsDiscussion forumsSocial networking sitesOnline games sitesHave a database as the “back end” that stores the information and a web page as the “front end” that the user sees
- 14. Storing dataIn a database information is stored in fieldsA field can be thought of as a “box” that holds the dataBobSmithFirst nameFamily nameSmithBob
- 15. Database fileAll the information about one person “Bob Smith” is a record
- 16. Database layoutAll the records of the different people are a database file
- 17. MS Access: TablesData in MS Access is typed into fields.Fields are stored in Tables.Below is a screenshot of a table showing the fields and their data types
- 18. MS Access: FormsTyping data into tables can be confusing to a user so we can use a Form to make a user “friendly interface”.Below is an order form for a Pizza Company database. The form makes it look more like a “proper programme”.
- 19. MS Access: QueriesTo process data in a databse we use a queryQueries can perform several different tasks in a database:Search for dataSort dataPerform calculationsDelete dataUpdate dataSQL = structured query language
- 20. MS Access: QueriesA query that sorts a list of Pizzas by nameA query that searches for an invoice and also has a calculation to generate the total price.
- 21. MS Access: ReportsReports are printouts.Data from the database is used to generate a report.Reports can be printed from tables or from the processed data by creating a report based on a query.Other calculations e.g. adding up totals can be done on the report.
- 22. MS Access: ReportsA report showing the orders for a given customer.
- 23. Relational databasesIn a relational database data are stored in fields in tablesThe tables are connected with common linked fields (relationship)
- 24. Relational databasesThis means that each piece of data needs only be entered once but is available in the entire databaseThis avoids the issue of data redundancy which might cause incorrect versions of data to be presentMultiple spellings of a persons nameErrors in other important data like phone numbers or bank details