Microsoft Access. Creating and Managing Databases

Transcription

1 Microsoft Access Creating and Managing Databases Microsoft Office 2007

2 Access Access... 2 When/if things go wrong... 5 Help... 5 What is a Database?... 6 Starting Access... 6 Creating a New Blank Database... 7 Using and Changing the View... 8 Tables... 8 Creating a Table in a New Database... 9 Creating a Primary Key... 9 Naming Fields Data Types Defining Field Properties Saving and Closing the Table Opening the Table Adding a New Field to the Table Moving and Copying Fields Entering Data/Records in the Table Editing Data in the Table Deleting Fields/Records Creating Table Relationships Linking Tables Deleting Relationships Queries What are Queries? Creating a New Query in Design View Adding and Removing Fields from the Query Showing a Field Setting Criteria Displaying the Results of the Select Query Saving, Closing and Opening a Query Multiple Criteria in a Query ICT Skills

3 Parameter Queries Grouping to Calculate in Queries Combining Text Displaying Parts of Text Sorting Records in a Query Action Queries Creating an Update Query Setting the Field to be updated Running the Query Viewing the Results Calculated Fields in Queries Calculations in Date Fields Forms Creating a Form in Access Adding/Removing Fields on a Form Deleting Fields/Objects Saving/Closing and Opening a Form Creating a Form using the Wizard Customise a Form in Design View Adding Command Buttons to the Form Resizing/Moving objects Viewing the Form Moving Between Records Entering Data using a Form Editing Records using a Form Deleting Records using a Form Form Properties Object Properties Using a Form as a Menu Reports Create a Report using Report Wizard Adding Fields to the Report Removing Fields from the Report Saving/Closing and Opening a Report ICT Skills 3

4 Customise a Report Grouping/Sorting the Data Report Properties Displaying and Previewing a Report Printing a Report Integration Copying and Pasting Data Moving or Copying and Pasting Exporting Data and Database Objects in Access Exporting Data and Database Objects from Access to Word Exporting Data and Database Objects from Access to Excel Supplementary Exercises Tables Relationships Queries Forms Reports Integration These notes do not explain every feature of the application therefore you are expected to make use of the Help facility. Note: This icon denotes important information read it carefully. Tasks This icon denotes a task which should be carried out to help you gain the skills required. 4 ICT Skills

5 USING A COMPUTER TO COMPILE A DATABASE ACCESS When you have completed these notes you should be able to: Find Microsoft Access and open it Insert data into a database Use Access s Help facility Identify the component parts of a database Create a table and enter records Edit a table Save, open and close a table Save, open and close a database Create, tables in a database Design and run queries on the information in the database Design and use forms Design and print reports Integrate Database Data with other Applications A database is an application used for storing and managing data. The database application most commonly used in the University is Microsoft Access The following notes will introduce some elementary features of databases using Access. They do not cover all aspects of the application. For information and instructions on other features use the Help facility within the application (see below). When/if things go wrong Before you start using this software, remember that when/if an error occurs try the following to rectify the situation, use the Undo option by choosing Undo, or clicking on the Undo command in the Quick Access toolbar. Help If there is a feature of Access you would like to use but do not know how, use the help facility within the application. This provides instructions on using all features of the application. Click the Help icon, this will open the Access Help dialogue box. The dialogue box will allow you to browse help topics or to specify a topic in the search field. Open a help topic or enter one in the search field and follow the on screen instructions. If all else fails, exit from the program (select the Office button button) and start again. and then Exit Access If you have any comments or queries, please contact the ICT Skills Unit: Room: M015, ground floor, George Moore building ICTSkills@gcu.ac.uk Tel: ICT Skills 5

6 What is a Database? A database is a collection of data related to a particular subject or purpose, such as staff records within an organisation, records for a sports club or student records for a University. A typical database consists of objects such as tables and queries. The objects outlined and explained in this booklet will be tables, queries, forms and reports. The database application most commonly used in the University is Microsoft Access which is a powerful database that can be used to store data. For example, a Student ICT Skills database could contain information on students who have passed or failed the ICT Skills module, their tutors, registration information and so on. Starting Access Access can be opened from the Start menu (displayed on the Taskbar at the bottom of the screen). After clicking the Start button, select All Programs, Microsoft Office then Microsoft Office Access This will open the Getting Started with Microsoft Access screen. This screen enables you to create a new database from scratch, open an existing database, use templates or browse Microsoft Office Online content as seen in Figure 1 below. Office Button Browse different templates Create a New Blank Database Help command Office Online pane with options to browse information on Microsoft Access Open Recent Databases by clicking on the database name, or clicking the More option to browse your computer for a saved database. Figure 1: Access Start Screen Task 1 Open Microsoft Access 2007 from the Start menu. 6 ICT Skills

7 Creating a New Blank Database To create a new Access database click on the Office button and select New. This will open the Blank Database pane on the right hand side of the screen, or click on the Blank Database command as shown in Figure 1 above. Note: The blank database will not contain any existing data or objects. At this stage you will be prompted to name the database, choose something logical which relates to the data. The default location where Access will save the database will be displayed below the File Name. For students working in University this should be your user workspace (H: drive). If you wish to save the database to a different location, click on the folder beside the File Name field. The File New Database dialogue box will open. Navigate to the location you wish to save the database, the file name you have already chosen will be showing and the file type will be displayed. Use either (*.mdb) or 2007 (*.accdb) format. Click OK to close the dialogue box. Next click the Create button, Access will create an empty table, Table1, in the Database window in Datasheet View ready for the insertion of data as shown in Figure 2 below. The Ribbon: Contains context sensitive groups of commands. The Navigation pane: Contains objects created in your database. You can switch between objects by clicking. New Table: Created with the database in Datasheet view ready for the insertion of data. Figure 2: Database Window Task 2 Create a new database. Name it ICT Skills Database (.accdb), change the path so it saves it in your user workspace (H: drive) and click on the Create button. Different objects within the database are colour coded for ease of use and are listed below: Tables have a blue band at the top Queries look like a double page Reports are green Forms have a red band at the top ICT Skills 7

8 Opening a database To open an existing database click the Office button and select Open from the drop down menu. The Open dialogue box will appear. Navigate to where the file has been stored. Double click on the name of the database that you wish to open. Saving and Closing the database Every time you enter or modify the data in your database Microsoft Access will automatically save the database to the location you have previously chosen. To close the database, select the Office button and choose the Close Database option from the drop down menu. This closes the database, but not Access. To close Access, select the Office button and choose Exit Access or click on the Close command on the main Access window. Note: If you close your database at this stage you will close the table which has been created. When you next open the database the table will not be showing. Using and Changing the View In Microsoft Access 2007 every object (table, query, form, report), has different types of view. Design View Datasheet View Form View allows you to create the actual structure and design of the object. used in tables and queries and allows you to view and enter data. used in forms allows data entry. Layout View used in reports and forms allows minimal control of the structure of the form or report and data entry and display. You can switch between the different views by clicking on the View command Views group on the Ribbon. in the Tables A new database is used to store the table(s) and all the queries, reports and forms that are needed to provide information from the database. A table is a collection of data on specific topics such as student details, results or course information. Tables are organised into columns called fields and rows called records. Each field in a table contains the same type of information for every entry. For example, if the table has a Surname field all entries in that field will be surnames. 8 ICT Skills

9 Creating a Table in a New Database Access When you create your database, it will create and open (by default) Table1 in Datasheet View ready for the entry of data. However when creating a table we recommend that you use the Design View option. This gives you full control over the table contents and properties. To do this, click on the bottom half of the View command in the Views group of the Home tab on the Ribbon. A drop down menu will appear with two view options showing. Choose the Design View option. You will be prompted to name and save your table at this point. The table is saved as part of the database file and its name should distinguish it from other tables in the database. When naming a table make sure you give it a meaningful name and one that links it to the information it contains for ease of reference later. Enter a name and click on OK. The table will now open in Design View as shown in Figure 3 and the table name appears in the Navigation Pane at the left hand side and on the Table tab at the top of the table. Table tab: shows the name of the table Data Type: This defines what kind of data you can enter in the field. Field Name: Name the fields with meaningful names. You can edit this later if necessary Row Selector Field Properties: These are a set of properties that allow additional control over how the data in a field is stored, entered or displayed. They are dependant on the data type used. Figure 3: Creating a table in Deign View Task 3 Change the table view from Datasheet to Design View. Name the table Student Details. Creating a Primary Key When your table opens in Design view you will notice that the first field has been automatically added. The field name is ID and the type is Autonumber. This field has been designated by Access as the Primary Key field for your table. When creating a table you should create a Primary Key. A primary key is a field (or combination of fields) that uniquely identifies and differentiates each record in a table. Each record in a table must have a unique (primary key) value. Fields that can have duplicates are never used for a primary key, for example, a person s surname should never be used as it can be duplicated, i.e. you can have more than one person with the same surname. Careful thought should be given to the table contents and fields at this stage prior to entering ICT Skills 9

10 data. If you have already identified an appropriate field that you wish to use as your Primary Key you may not want to use the one that has been set by Access. The default primary key can be either changed or removed. To change the Primary key, simply delete the name and type the values you wish. Alternately you can delete the primary key. To do this, click on the Primary Key icon in the Tools group on the Table Tools Design tab in the Ribbon. This command will no longer be highlighted and the primary key symbol will disappear from the row header. Once you have removed the Primary key symbol you can delete the information from the Field Name and Data Type columns. To set a primary key you must be in table Design view. Select the field you want to set as the primary key. Click on the Primary key icon from the Ribbon. You will see the Primary key symbol appearing in the row selector column. If you want to have a combination of fields for a primary key you have to select the fields before you click the Primary key icon. Note: You MUST have a Primary Key for your table. A primary key within a table is the field or set of fields which have a unique value for every row (record) within the table. Task 4 Remove the default Primary Key set by Access in Design view. Naming Fields When creating the fields for a table their name, data type and properties have to be defined. Field names should be meaningful so that the data is easy to identify, e.g. Surname, Date of Birth and Address. Task 5 Enter the following field names in the table: Matriculation Number, Surname, Forename, Course Code, Level, DOB, Phone Number, Pass, Score Task 6 Create a new Primary Key or choose one of the existing fields to be Primary Key for your table. Note: Matriculation Number is a good choice for this as it is a unique number for each student. Data Types In order to build the table you must decide on the data type of each of the fields. When you name fields without defining a data type Access inserts Text as the data type by default. There are a number of different data types. You must decide on the appropriate 10 ICT Skills

11 data type for each field, and assign it to the field name when you are designing your table. For example, if you have a field name of Score in a student details table it could contain data that is in number format. The number data type should only be used when mathematical calculations are being carried out on the data; otherwise it is recommended that a text data type is used. A surname would normally contain data that is text. To do this click on the Data Type cell next to the field name, a downward arrow will show. Click on the downward arrow and an options list will appear with the different data types. Choose an appropriate type from the list by clicking on it. A description of each type is shown in the table below. Note: Check the different data types available before choosing. Consideration should be given to the data being entered (e.g. phone numbers start with area codes, may contain symbols and should therefore be a text field). Types of data include: Data Type Description Text Allows the entry of letters and numbers to a maximum length of 255 characters. The default field size is 50. Memo Number A character string with a maximum length of about 65,000 characters. A memo field cannot be used as a primary key. There are many different number subtypes available in Field Size. Some of them are: for real numbers Double (15 places, 8 bytes) and Single (7 places, 4 bytes); for integers Long Integer ( 2.1 to +2.1 billion, 4 bytes, no decimals), Integer ( 32 to +32 thousand, 2 bytes, no decimals) and Byte (values 0 to 255, 1 byte, no decimals). Number format should not be used for calculations involving money, the currency format should be used. AutoNumber Automatically generated sequencial number. Numbering starts with the number one and increases by one each time data for a new record is entered. Usually used as a unique identifier, i.e. a primary key. Yes/No Date/Time Currency Hyperlink Stores logical True or False results Stores dates and times. A variety of display formats are available. This data type is used for money. It is better not to use the Number data type for currency values because numbers to the right of the decimal point may be rounded up. Can hold 15 places to the left of the decimal and four places to the right. Takes up 4 bytes. Used for storing web addresses. Task 7 Choose appropriate data types for the fields in your table. ICT Skills 11

12 Defining Field Properties Once a database table has been created, the fields named and the data type chosen, it is recommended to make further refinements to the fields by setting field properties. The properties you can set for each field are determined by the data type you select. For example, if the data type is text you can define the length of characters in the field. To do this you must be looking at the table in Design View. Select the field whose properties you want to set by clicking in it. Look down at the Field Properties section at the bottom of the table and click the property you want to set in the General tab. When you click most of the options a downward arrow appears, by clicking on the arrow a list of options appears for that particular property. Click on the property value you wish. Field Properties General tab showing properties Figure 4: Field Properties Section Some of the most common properties are: Field size Depending on the type selected there will be different options. If it is a text field type, the default field size is 255 characters, which you can change to suit your data. If the field type is number you can change the field size to fit the type of number you want, i.e. Byte, Integer, Long Integer, Single, Double and so on. Format Not all field types can be formatted. To check click on the field type, then on the format option under field properties, click on the downward arrow to see if there are any format options. A drop down list should appear if the field can be formatted. Some examples of field types that have a format options are Date/time, Number and Currency. Caption Use this option if you want the caption displayed in the column heading of the table in Datasheet View to be different from the field name. For example if your field name is DOB you may want to display Date of Birth as a caption of the column heading. Required The default option is No. Set this option to Yes if you require a value entered in this field. This is useful for fields that store names for example. Default value If you want to set a default value for a field you can do it by using this option from the properties. When you have a field that usually has the same value entered into it this is a good option to use and saves on entering data. The default value can be changed if required and it will not affect data that has already been entered. 12 ICT Skills

13 Task 8 Reduce the size of the text fields to a more appropriate size. Amend the Properties of the following fields: Surname to be a required field; Course Code to field size 10; DOB field to Short Date format; Caption the DOB field to Date of Birth; Caption the Matriculation Number field to Matric No and the Score field to be Single field size. Input masks A customised display can be created for the information which is entered into the table using an Input Mask. An Input Mask allows the information in a field to be displayed in a particular format by using a set of characters known as placeholders. For example, all of the letters in a field can be shown in uppercase, for example a course code could be BAAC. Input masks are mostly used in text fields. The list of placeholders and their meaning is displayed below. Some examples are listed here: Placeholder Meaning 0 Digit. Entry required. 9 Digit. Entry optional. # Digit, a space, or a plus or minus sign. If left empty, Access enters a blank space. L Letter. Entry required.? Letter. Entry optional. A Letter or digit. Entry required. a Letter or digit. Entry optional. & Any character or space. Entry required. C Any character or space. Entry optional. > All characters that follow (placeholders must be entered for them) appear in uppercase, e.g. >???????? will allow BAAC, uppercase letters only < All characters that follow appear in lowercase. e.g. <LLLL will allow baac \ Forces Access to display the character that immediately follows. This is the same as enclosing a character in double quotation marks. For example \A will be displayed as A. Password In Design view for tables or forms, setting the Input Mask property to Password creates a password entry box. When users type passwords in the box, the characters are stored but asterisks (*) are displayed. Type Input mask example Data Example and Explanation Number (9999) () Requires the phone number to be entered but entering the code is optional. Text >L<?????????????????????? Maria First letter is capital and required and the rest of the word is optional and lower case ICT Skills 13

14 Task 9 Apply an Input Mask so that the Course Code is entered in uppercase. Create an input mask of your own for some of the other data. Validation rule By using a Validation Rule you can control the data entered by a user. For example a validation rule can enforce maximum and/or minimum values for number or date types or can enforce a desired number of letters or numbers. Some of the symbols used in Validation Rules with a LIKE operator are:? for any letter # for any digit * for any number of characters Note: Text should be put in quotation marks and dates should have a, # before and after the date. For example in a table if we wish the course code to be entered in its short four letter format (BA Accountancy is expressed as BAAC) then we could insert the Validation Rule????. This will ensure that only four letters are entered for that field. When a Validation Rule is entered there should be accompanying Validation Text. This is a customised message which appears if the value entered violates the rule you have set. Here are some examples of validation rules and texts: Validation rule Validation text >=0 You must enter a non negative number. 0 or >100 Value must be either 0 or greater than 100. BETWEEN 70 AND 100 The value entered must be between 70 and 100 inclusive <#01/01/2010# The date should be before >=#01/01/2007# AND <#01/01/2008# Date must be in <=Date() The date cannot be in the future. Date() will return today s date LIKE???# The value must be 3 letters and 1 number Task 10 Enter the Validation Rule in the Properties section of the Score field to ensure that the Score is between 0 and 40. Enter the following Validation Text: The number entered must be between 0 and 40. Note: Data is validated as it is entered. If the data entered breaks the validation rule that has been set, the validation text will appear, if there is no validation text an error message will appear. 14 ICT Skills

15 Saving and Closing the Table Access Once the structure of the table has been designed it should be saved again. To save a table, click on the Office button, choose Save. Changes to the table will now be saved. To close a table you must click on the Close icon at the right hand side of the Table tab. You will be prompted to save any changes you have made to the table if you have not already done so. Note: Remember you have only closed the table at this stage, not the database. Your Database window will now be blank and the objects created listed in the Navigation Pane in the left hand side. Task 11 Re Save the table. Close the table. You will now see the Student Details table in the Navigation Pane. Opening the Table You can open a table in either Design or Datasheet View. Double clicking on the table name in the Navigation Pane will open the table in Datasheet View, you can then change to Design view by using the View command from the Ribbon. Alternately you can right mouse click on the table name in the Navigation Pane, a drop down list will appear with options to open the table, or to choose Design View to open. Adding a New Field to the Table Once you have created your table you may wish to add new fields. To add a new field to your table, open the table in Design View and in the next available field type in the field name and choose an appropriate data type. You should then define properties appropriate to the field type. Once you have made the changes required you will be prompted to save the changes before you can go back into datasheet view to add the information into this field. Task 12 Open the Students Details table in Design view. Create a new field in the table with the following settings: The new field name is Year Passed. Choose an appropriate data type, format and any input mask or validation rules you feel are required. ICT Skills 15

16 Moving and Copying Fields Once you have inserted the fields into your table you can choose to change their order. Note: This should be done before any data is entered as it may permanently delete the data ruining the integrity of your table. Careful thought must therefore be given to your table content and design before you start. To move a field you must be in Design View. Select the field to be moved by clicking on its field selector at the beginning of the row, click on the Home tab, Clipboard group and the Cut command, or select the row, right mouse click and choose Cut from the drop down menu. Once you have cut the row you must remember to paste it in the new location. To do this click in the cell where the field is to be moved and click on the Paste command from Clipboard group, on the Home tab, or right mouse click and choose Paste from the drop down menu. You can also copy a field by selecting it, using the Copy command from Clipboard group of the Home tab, or right mouse click and choose Copy from the drop down menu. Make sure that you have created an empty row where you want the new field to be. To create a new field in the body of the table, click on the field after the required location, click on Insert Row command from the Tools group on the Table Tools Design tab. Then click in the cell where the copy of the field is required and use the Paste command from the Clipboard group on the Home tab, or right mouse click and choose Paste from the dropdown menu. This is useful if you have a field which you wish to duplicate and then modify. View command Primary Key command Row selector Table Tools Design tab Insert Row and Delete Row commands Figure 5: Table in Design View showing Table Tools tab Task 13 Copy the Year Passed field. Paste it at the bottom of the data. Change the name to Year of Entry and save the table. 16 ICT Skills

17 Entering Data/Records in the Table Access Once you have created your table and entered the field details you must enter the data. Until now you have only used Design View. To enter data a table must be opened in Datasheet View. Once a table is open it is possible to switch from the Datasheet View to Design View and vice versa using the View command in the Ribbon, as shown in Figure 5 above. In Datasheet View the headings of the columns are the field names you have entered previously or the captions of these fields if there are any set. Enter the information for each field and tab along or click in the next field to enter the information. Each row in the database is a record and as you complete each record it is automatically saved into the table in your database file. Task 14 Change to Datasheet View and enter the following information in the Student Details table. Matric No Surname Forename Course Code Level Date of Birth Phone Number Pass Score Year Passed Year of Entry Brown John BAAC 1 15/09/ Yes Jones James BSOO 2 13/07/ No Smith Gordon BARM 1 19/01/ No Davids Emily BSOD 3 22/03/ Yes Nelson Timothy BSIS 1 01/04/ No Brown Joseph BAAC 1 05/09/ Yes Andrews Maureen BSOO 2 29/04/ Yes McBride Josephine BARM 3 31/12/ No Thomson Tamara BAAC 1 25/06/ Yes Adams Henry BSCG 1 30/12/ No Sweeney Liam BSCG 2 01/01/ No Editing Data in the Table Once you have entered records in a table they are available to be used e.g. sorted, retrieved. These records may be edited and changed, therefore if you find there are any errors you can change them by editing the contents of the record. To edit a record you simply place the cursor in the cell which contains the data and change it. You can move quickly and easily through records using the Record Navigation panel at the bottom of ICT Skills 17

18 the Datasheet window. You can move back, forward, to the beginning or the end of the records by clicking on the buttons as indicated in Figure 6 below. You can also search the table for a specific entry by clicking in the Search box and entering the data that you wish to search for. First Record Previous Record Next Record Last Record Search Table facility Figure 6: Record navigator Task 15 Edit the following information: John Brown course code should read BAFS Timothy Nelson date of birth is 04/01/1980 Deleting Fields/Records To delete a field you can be in either Datasheet or Design View. Choose the field you wish to delete by clicking on it then click on downward arrow next to the Delete command in the Records group of the Home tab in the Ribbon. A drop down menu will appear with different deletion options, choose the deletion option you require by clicking on it (see Figure 7 below). Prior to deletion you will be prompted to confirm permanent deletion of the field. Click on Yes to delete the field. If you have entered any information in that field it will be permanently removed. Figure 7: Delete command within the Records group To delete a record(s) in a table you must be in Datasheet View. Select the record or records you wish to delete by clicking on them and click on the Delete command (see Figure 7 above). Access prompts you to confirm the deletion. Click on Yes to delete the record or No to stop the deletion. Note: Deletion of fields and records is permanent and cannot be undone. Task 16 Delete the following information: Delete the Level field from the table and the information for Gordon Smith Save and close the Student Details table. 18 ICT Skills

19 Creating Table Relationships Most databases have more than one table from which to extract data and some could have hundreds. These tables should be linked to create relationships between the tables in order to ensure the data in the tables is consistent. Note: Before you start your database careful thought must be given to the information it should contain and what you want to do with it. In order to get the most from Access you should create relationships between tables. These are created by linking fields which have common data types, or the field from one of the linked tables should only contain data that exists in the other table. Data can then be accessed and viewed without reorganising all of the data within the table(s). There are three main categories of relationship: A one to one relationship (1:1) This occurs when there is only one instance of a table relationship with another. For example, in a Matric No table there will be a list of all used Matric numbers, in a Student Details table there will be student information listed. A one to one relationship exists between a matric no and a student. There is only one matriculation number associated with one student. A one to many relationship (1:m) This occurs when for each instance within one particular table there are many instances in another. For example, each student is only allowed to register on one programme, but the programme can have many students registered. A many to many relationship (m:m) This occurs when for each instance of one particular table there are many instances of another. For example, if a student was allowed to register on more than one programme then the link between students and programmes would be many to many. Task 17 Create a Course Code table containing the following information: Course Code Number of Students Department BAAC 250 CBS BARM 115 CBS BSOO 400 NMCH BSIS 100 NMCH BSOD 326 NMCH BSCG 310 ESD BEPP 125 LSS BAAG 215 ESD BAFS 186 CBS Using the information from earlier in the booklet, select the Course Code as the Primary key. Also choose appropriate: data type; field size; format; input masks; and validation as you see appropriate. Save the table as Course Code and close it. ICT Skills 19

20 Linking Tables Once your tables have been created you can create links between them. To do this click on the Database Tools tab on the Ribbon, and click on the Relationships command in the Show/Hide group as shown in Figure 8 below. Figure 8: The Relationships command. The Show Table dialogue box will appear, as shown in Figure 9 below. Figure 9: The Show Table dialogue box in the Relationships Area. Click on the table names you wish to create links to and click on the Add button. The table(s) will appear on the pale Relationships area behind the dialogue box. Once you have selected all of the tables you wish, close the Show Table dialogue box by clicking on the Close button. Your tables will now be in the Relationships area (see Figure 10 below). Tables are identified by their name which appears in the blue title bar of the table. The primary key in each table is shown with a small key beside it. Primary Key Foreign key Figure 10: Tables in Relationship Area Note: You can move the tables within the grey area by clicking and dragging on the blue title bar. You can also resize the tables to display the contents by dragging on one of the table frames. 20 ICT Skills

21 Task 18 Add your tables to the Relationships area. To create a relationship between tables you must firstly identify common fields between them. Highlight the common field in one table by clicking on it, it will become orange, then hold and drag to the common field in the related table and drop it on the corresponding field name, (the cursor will change to look like a stop sign until it reaches the other table when it become a +). The field in the related table (the table where this field is not a primary key) is known as the foreign key. The Edit Relationships dialogue box will appear, see below. Create Button Enforce Referential Integrity check box Figure 11: Edit Relationship Dialogue box This dialogue box will provide information about the relationship you are creating, and give you the option to check the Enforce Referential Integrity box. Enforcing referential integrity will enable the database to check that entries in fact exist between the primary and related tables when they are entered. For example if you link the Student Details table with the Course Code table and then enter a course code in the Student Details table which does not exist in the Course Code table you will get an error message. Once you have checked the Enforce Referential Integrity box click on the Create button to create the relationship. You will see that the tables are now joined by a black line showing the relationship. Line of Relationship Figure 12: Relationship Line between tables. When you have created your relationships close the Relationship window by clicking on Close command. You will be asked if you want to save the changes to the layout of the Relationships. If you are happy with the changes made click Yes. Note: The 1 and infinity symbols show that a 1:many relationship has been created. ICT Skills 21

22 Task 19 Create a relationship between the Student Details and the Course Code tables. Note the type of relationship that has been created. Close the Relationships window. Note: Remember you can move the tables about if you need to. Deleting Relationships Once you have created relationships, and find that you have made a mistake you can delete the relationship. To do this click on the Database Tools tab on the Ribbon and choose the Relationship command, from the Show/Hide group. The Relationships window will open displaying the tables and relationships you have already created. To delete a relationship click on the black line between the two tables, it will then become bold. Click on the Delete command in the Records group of the Home tab on the Ribbon, a drop down menu will appear, choose the Delete option from this menu or simply press the Delete key on the keyboard. You will be asked if you are sure you wish to permanently delete the relationship if you choose Yes the relationship will be removed. 22 ICT Skills

23 Queries What are Queries? Queries are used to search/retrieve and update specific records from database table(s), dependant upon your needs. For example, to look at a specific group/course of students, or to find pass/fail records. Queries retrieve a particular set of records and fields based on set criteria. Creating a New Query in Design View There are many different types of queries. The default type is the Select Query which forms the basis of all of the other query types created. It is recommended that you create a query in Design View. This involves two stages: Open your database if it is closed. The database will open and display your Database window and Navigation Pane showing all of the objects already created. From the Ribbon click the Create tab and the Query Design command from the Other group, (see Figure 13 below). Figure 13: The Access Create tab A new query will open with the default name Query1 and the Show Table dialogue box will be displayed. The Show Table dialogue box will list all of the tables in your database. You must choose the table(s) which contains the information that you wish to use to create the query. Click on the table name(s) and click on the Add button to add tables to the query. The table listing all of the fields will appear in the Query tab that has opened. Once you have added all of the tables you wish you should click on the Close button. When the Show Table dialogue box is closed the Query Tools Design tab will open on the Ribbon, (see Figure 14 below). Figure 14: The Show Table Dialogue Box Create tab Query Design Command Other Group Query Tools Design tab Show Table dialogue box click the table names you wish to take the fields from to add the table to the query. Query Fields Fields from tables that are included in the query Show boxes if these boxes are checked (they have a tick in them) it means that this field will be shown when the results of the query are displayed. ICT Skills 23

24 Task 20 Open a Query in Design view. Add the Student Details table to it. Close the Show Table dialogue box. Note: If you add more than one table their Table Fields list boxes will be displayed side by side in the upper section of the Query Design window. Adding and Removing Fields from the Query You must now select the fields to be used in the query. It is not usually necessary to use all of the fields in the table. For example Students names, Matric numbers and Course codes may be all that is needed to determine the exact number of students studying on a particular course within the University. There are different ways to add fields to a table as described below. Adding all the fields in the table to the query The simplest case is where we want to include all of the fields in the table. Double click on the title bar of the Table Fields list box. This will select all of the fields (you will notice they have turned orange). Click on any of the selected fields and drag to the field cell(s) in the lower section of the Query window. The pointer should look like a stop sign until it reaches the query fields when it turns into a + with a box around it. When you release the mouse button all the field names will have been added to the query. You can use the horizontal scroll bar to move to the right, as all the columns may not fit on the screen. Task 21 Add all of the fields from the Student Details table to the query. Adding individual fields from the table to the query There are three main ways to add individual fields to the query 1. Double Clicking: Double click on the name of the field required in the Table Fields list box in the upper section of the Query Design window. It will appear in the next available column in the grid at the bottom part of the window. 2. Use the Drop Down List: Click in the Field cell in the lower section of the window. A downward arrow appears at the end of the cell. Click on it and a drop down list of field names will appear. Find the name of the field required, if necessary scroll through the list, click on it and it will appear in the field cell. 3. Drag and Drop: Click on the name of the field required in the Table Fields list box in the upper section of the window. Drag and drop this field into the required field cell in the lower part of the Query window. If you drop the field onto a column containing a field then a column will be inserted to contain the new field. 24 ICT Skills

25 Removing fields from the query Access Fields may be removed individually or in blocks from the query. To remove a single field from a query, click on the title bar of the field (the pointer will change shape to a downward arrow ). The field will become black, press the Delete key. To remove all the fields from a query select the column as above, it will become black, hold and drag to select all the columns. Press the Delete key. Task 22 Remove the following fields from the query: DOB and Year of Entry. Showing a Field By default, when a field is added to the query it is selected, that is it will have a tick in the Show box this means that when the results of the query are displayed this field will show as output. For certain queries you may not want all of the fields to show. To do this you need to click (deselect, remove the tick) the Show box of that field (see Figure 14) in Design View and this field will not be shown when the outputs are displayed. Task 23 Deselect the field Year Passed. Setting Criteria Criteria are filters that you place on a query field to identify the specific records you want to get. For example, instead of viewing all of the students who have passed the ICT Skills assessment, you can view students who have passed and who belong to a specific programme. To do this, you specify criteria that limit the results to records with a specific course code. For example in the Criteria row in the Course Code field you can specify a specific course code to ensure that only students from that particular course are shown. Task 24 Add criteria that limits returns to students with the BSOO Course Code. Displaying the Results of the Select Query You can view the results from a simple select query by switching from Design View to Datasheet View. You can do this by clicking on the top half of the View command on the Ribbon. There is a downward arrow at the bottom of this command. If you click the arrow a drop down menu will appear giving the different view options. ICT Skills 25

26 Task 25 Switch to Datasheet View and display the results of the query. Saving, Closing and Opening a Query Saving a query To save a query, go to the Office button and choose Save As. The Save As dialogue box will appear prompting you to name the query before saving (see Figure 15). Keep the name of the query short but appropriate to the information it contains. The query name will now appear in the Navigation Pane at the left hand side of the window, and the name of the tab changed from Query1 to the one chosen. Figure 15: Query Save As dialogue box A query should be saved before it is closed, however if you forget and try to close it before you have saved it a dialogue box will appear prompting you to save it. If you choose Yes at this point a Save As dialogue box will appear with the default name Query1. Change the query name to something appropriate and click OK, this will save the query to the database. Note: The query will be listed under the student details table as this is where the information for it came from. Task 26 Save the query as BSOO List. Closing a query You can close the query by clicking on the Close command at the top right corner of the Query tab. If the query has not been saved before you will be asked to save it now. Opening a query To open a query you can double click on the Query name from the Navigation pane on the left hand side of the Database window. Alternately you can open the query by selecting it from the Navigation pane and right mouse clicking it, a drop down list will appear, choose Open from the list to open in Datasheet View or Design View which will open it in Design View. 26 ICT Skills

27 Multiple Criteria in a Query You can use more than one criterion in a query. This can be done by using the logical operators AND/OR. To combine criteria in different fields you should enter your criteria in the same row of the design grid, this will ensure that criteria (A) AND (B) will be considered and that records which conform to all criteria are displayed. If the criteria are entered in different rows of the design grid, this will ensure that (A) OR (B) will be considered and that records which conform to either criterion are displayed. The LIKE operator can also be used to return results when you do not have a specific value to search for. For example, a student may have registered as A Smith, as you do not know their full forename, only the initial you could use the criteria: Like A* in the criteria row of the forename field of the query, this will return all students whose forename starts with A. Examples of criteria expressions The following characters can be used in criteria with the LIKE operator: Character Usage Example * Matches any number of characters. Pa* will find Patrick, Patricia and so on? Matches any one alphabetic character W?t will find wit and wet # Matches any one numeric character 2# finds 20, 21, 22 Field Expression Description Pass Yes Displays all students that have passed the ICT Skills assessment. Mode of Full time OR Part time Displays all full/part time students Study Name Like T* Displays all students whose names starts with the letter T. Name >= M Displays students whose names start with the letters M through Z. Task 27 Open the query BSOO List. Re Save it as BSOO Pass List and add further criterion that limits your returns to students from the BSOO programme and who have passed the ICT Skills assessment. View the results in Datasheet View. Save and close the query. Note: The Pass field is a Yes or No field, therefore students who have passed will be a Yes entry. Task 28 Open the BSOO List query. Add further criteria that limits the returns to students with a surname which starts with J. View the results, save as J BSOO Students and close the query. ICT Skills 27

28 Parameter Queries If you run the same select query, but for different values you can save time by creating a Parameter Query. A parameter query allows you to view a select query but which prompts the user of the database for specific input for the query every time it is run. In the previous example we created a query to view students from a particular course code from our database table(s), however there are many course codes and we may wish to view the list of students from various courses. Rather than setting up a query for each course code we could set up a parameter query which prompts the user to enter a value to show the results required each time. To do this you create your query using the instructions on pages In the Criteria row of the query, enter the text you wish to be displayed which will describe the parameter you wish to set. If the parameter was the course code, you could type [Enter a Course Code], in the criteria row. The parameter text must be enclosed in square brackets as shown in this example. To view the query you would click on the Datasheet View icon. When you do this the Enter Parameter Value dialogue box will appear as shown in Figure 16 below. Enter the value you are looking for, in this example a Course code, and the results of the Query in Datasheet View will open. Figure 16: Enter Parameter Value dialogue box Task 29 Create a query in Design View using the Student Details table. Add the Matriculation Number; Surname; Course Code; Year of Entry fields. Enter a parameter to display only students who entered the course in View the results of the query, save the query with the name Year of Entry. Close the query. Open the query and re run it to display students who entered the course in Multiple Parameters You can also create a parameter query which has multiple parameters. If for example you wished to know the year students entered a particular programme you would create your query and in the criteria row you would specify the parameters for each field to be included. When you view the results of this query the Enter Parameter Value dialogue boxes will appear starting from left to right in the query criteria row, and every parameter will be applied. After you have entered all parameters required the results will be displayed. 28 ICT Skills

29 Task 30 Create a query in Design View using the Student Details table. Add the Matriculation Number, Surname, Course Code, Year of Entry fields. Set parameters in the Course Code and Year of Entry fields and then change to Datasheet View. When prompted enter BSOO programme and Year of Entry 2002 to test the query. Save the query and name it Course and Year Query. Grouping to Calculate in Queries There are many types of calculations (Expressions) that can be performed in a query from simple additions and multiplications to more complex calculations. These calculations can be performed on specific groups or on the entire contents of a table(s) simply and easily. To enter a calculation you can either type the calculation in or use the Expression Builder tool which is available. The following table outlines some of the calculations which can be performed: Function SUM AVERAGE COUNT MINIMUM MAXIMUM STANDARD DEVIATION VARIANCE Description Add the values in a numeric field Shows the average of the numbers in a field Counts the number of each item in a field Shows lowest value Shows highest value Measures the spread of the averagevalues of a field Measures the variance among the average values of a field Functions To create a grouped query with calculations follow the steps to create a select query on pages Once the table(s) you wish the fields to be taken from have been added, select the fields which you wish to use for the calculation. Then click on the Totals command in the Show/Hide group of the Query Tools Design tab on the Ribbon. This will add the Total row to your query design grid (see Figure 17 and Figure 18 below). Within the Total row you will see the words Group By, allowing you to group the selection by a field and then use various statistical functions on these groups. To choose a function, click on the downward arrow beside Group By. Scroll to the function required and click on it. The function name will now replace Group By. To view the results of the query click on the View command and change to Datasheet View. Totals icon Total field Figure 17: The Totals icon Group By drop down list Figure 18: The Total field in Design View ICT Skills 29