«Information and communication technologies» Practical work 5. Databases

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1 Practical work 5. Databases Objective: Understand that one of the advantages of a computer-based database is the ability to search for data quickly. Know what data types are. Be able to choose the correct data types for specific items of data. Learning Outcomes: Understand how to set up a database by using fields, data types and validation rules. Know how to import data into a database. Be able to create a database from scratch by following a list of instructions. Vocabulary 1. Database 2. Record 3. Fields 4. Data Type 5. Primary Key 6. Foreign Key 7. Referential integrity 8. Relationships 9. Queries 10. Forms 11. Reports 12. Macros 13. Modules База данных Запись Поля Тип данных Первичный ключ Внешний ключ Ссылочная целостность Отношения Запросы Формы Отчеты Макрос Модули DEFINITION: A database is a collection of data or information which is held together in an organised or logical way. The Microsoft Access Database is made up of 7 major components: Tables; Relationships; Queries; Forms; Reports; Macros; Modules. Tables Databases store data or information in tables, just like the one below:

The table allows you to see all of the records stored in the database. Records As you saw previously, each table can store a great deal of data. Each table contains a lot of records. thing.

What information could you find in the record for Cat Woman? 2. What records do you think are stored on the database at your school? 3.

2 The table allows you to see all of the records stored in the database. Records As you saw previously, each table can store a great deal of data. Each table contains a lot of records. thing. DEFINITION: A record is all of the data or information about one person or one In the table below, all of the information about each cartoon character is stored in a 'row' or 'record'. 1. What information could you find in the record for Cat Woman? 2. What records do you think are stored on the database at your school? 3. How about your school library - what records would be stored on their database? Fields Each table contains a lot of records. A record is made up of lots of individual pieces of information. Look at Wonder Woman's record: it stores her first name, last name, address, city and age.

Each of these individual pieces of information in a record is called a 'field'. DEFINITION: a 'field' is one piece of data or information about a person or thing. 1.

3 Each of these individual pieces of information in a record is called a 'field'. DEFINITION: a 'field' is one piece of data or information about a person or thing. 1. What fields can you find about Tweety Bird? 2. What fields do you think would be stored in your student record in the school database? 3. What fields would be stored in a book record in the school library database? Data Types When you are about to set up a database, you need to think about the 'data type' which you will use for each field. The most common data types are: Data Type Alphanumeric or Text This allows you to type in text, numbers and symbols Number This allows a whole number or a decimal number Only numbers can be entered, no letters or symbols Examples Forename: James Surname: Smith Address: 73, High Street Postcode: CV34 5TR Car Registration: EP06 5TV TelephoneNumber: *

Data Type Currency This automatically formats the data to have a or $ or Euro symbol in front of the data and also ensures there are two decimal places.

4 Data Type Currency This automatically formats the data to have a or $ or Euro symbol in front of the data and also ensures there are two decimal places. Date/Time This restricts data entry to 1-31 for day (28 or 30 in appropriate months) and 1-12 for month. It checks that a date can actually exist, for example, it would not allow 31/02/06 to be entered. It formats the data into long, medium or short date/time Auto number This data type will automatically increase by 1 as records are added to the database Examples 5.75 $54.99 Long Date: 20 February 2006 Medium Date: 20-Feb-06 Short Date: 20/02/06 Long Time: 18:21:35 Medium Time: 06:21 PM ShortTime: 18:21 Record 1: 1 Record 2: 2 Record 3: 3 Logical, Boolean, Yes/No This datatype is often referred to as different things, you may hear it called 'logical', or 'boolean' or 'yes/no'. All it means is that the data is restricted to one of only two choices Yes/No Male/Female Hot/Cold On/Off * You would think that 'telephone number' should be a 'number' data type. However all telephone numbers start with a 0 and you can't put a 0 in front of a 'number' data type, so telephone number needs to be set as a 'text' data type. Here is a database table with the different data types set up for you to see:

Field Length Once you have chosen your data types, you need to think about the best 'field length' for each field. Most databases will have a default field length set up, in this case it is 50.

5 Field Length Once you have chosen your data types, you need to think about the best 'field length' for each field. Most databases will have a default field length set up, in this case it is 50. This means that each text field is able to store up to 50 letters, numbers or symbols. In some situations, you may need to use all 50, but think about forenames. How long is the longest one you can think of? Probably around 12. What about surname? Even a double-barrel surname is unlikely to need more than 20 letters. The reason that you shouldn't just leave the field length as the default number is because every single character space allowed takes up one byte of storage space in the database, so a field size of 50 would need 50 bytes of storage. On its own, that doesn't sound a lot, but multiply that by all of the fields in the database and then by every single record being stored and you could soon have a large and unwieldy database that becomes a bit slow and sluggish. What field size do you think would be sensible for the following: Postcode? Telephonenumber? Carregistrationnumber? Town? County?

Primary Key Therefore, it is important that every single record in a database has something to uniquely identify it and this is called the 'Primary Key' or sometimes the 'Key Field'.

Referential integrity Every foreign key value has a matching value in the corresponding primary key. Referential integrity uses these to ensure that there are no orphan records i.e. it prevents you from deleting related records.

6 Primary Key Therefore, it is important that every single record in a database has something to uniquely identify it and this is called the 'Primary Key' or sometimes the 'Key Field'. Foreign Key DEFINITION: A foreign key is used to link tables together and create a relationship. It is a field in one table that is linked to the primary key in another table. Referential integrity Every foreign key value has a matching value in the corresponding primary key. Referential integrity uses these to ensure that there are no orphan records i.e. it prevents you from deleting related records. Referential integrity can also alert you if you try to delete a record which is related to another one. It can also be used to cascade changes made to the database.

7 Queries Are the means of manipulating the data to display in a form or a report. Queries can sort, calculate, group, filter, join tables, update data, delete data, etc. Their power is immense. The Microsoft Access database query language is SQL (Structured Query Language). The need to know SQL is not required in the early stages of learning Access. Microsoft Access writes the SQL for you, after you tell it what you want, in the Design view of the queries window. Forms Forms are the primary interface through which the users of the database enter data. The person who enters the data will interact with forms regularly. The programmer can set the forms to show only the data required. By using queries, properties, macros and VBA (Visual Basic for Applications), the ability to add, edit and delete data can also be set. Forms can be set up and developed to reflect the use they will be required for. Reports Reports are the results of the manipulation of the data you have entered into the database. Unlike forms, they cannot be edited. Reports are intended to be used to output data to another device or application, i.e. printer, fax, Microsoft Word or Microsoft Excel. Macros Macros are an automatic way for Access to carry out a series of actions for the database. Access gives you a selection of actions that are carried out in the order you enter. Macros can open forms; run queries, change values of a field, run other Macros, etc. the list is almost endless. Modules Modules are the basis of the programming language that supports Microsoft Access, The module window is where you can write and store Visual Basic for Applications (VBA). Advanced users of Microsoft Access tend to use VBA instead of Macros. If you would like to learn VBA, I have a simple step by step lessons. Questions: 1. Creating a new database? 2. Setting up fields? 3. Changing the field size? 4. Selecting appropriate data types? 5. Setting up formatting e.g. date? 6. Primary key? 7. Required field? 8. Validation rule? 9. Lookup table? 10. Creating a form? 11. Entering records?

Level 6 Relational Database Unit 3 Relational Database Development Environment National Council for Vocational Awards C30147 RELATIONAL DATABASE

C30147 RELATIONAL DATABASE Level 6 Relational Database Unit 3 Relational Database Development Environment National Council for Vocational Awards This module has been developed to further the learner s