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SUNY Morrisville-Norwich Campus-Week 8 CITA 130 Advanced Computer Applications II Spring 2005 Prof. Tom Smith Objectives Questions from Last Week Review of Basic Database Functionality Microsoft Access 2003 Tutorial 1 – Introduction To Microsoft Access 2003 Define some key Access terminology Field – A single characteristic or attribute of a person, place, object, event, or idea. Record – A set of related field values. Table – A collection of records that identify a category of data, such as Customers, Orders, or Inventory. Illustration of fields, records and a table Relational database and keys A relational database is a collection of tables that are related to one another based on a common field. A field, or a collection of fields, is designated as the primary key. The primary key uniquely identifies a record in the table. When the primary key of one table is represented in a second table to form a relationship, it is called a foreign key. Relating tables using a common field Use the task pane to open a database Open an Access database table To open a table you must first open a database: In the database window, select Tables on the objects bar In the list of tables, select the table you want to open and click on the Open button When a table is open it is in Datasheet view, which shows the table's data as a collection of rows and columns Each row in the Datasheet view represents a record in the table A table in datasheet view Learn how Access saves a database The Save button in Access differs from the Save button in other Windows programs. When you press the Save button in Access, you are saving the design of the Access objects and NOT the data itself. Access saves data as it is entered For this reason, the location at which you are storing your database must always be accessible while working with a particular database. If the database is located on a diskette, the diskette must be in the diskette drive at all times while working with this particular database What is an Access query? If you want to see just a portion of the data in a table you can create a query. A query is a question you ask about the data stored in a database table. Access responds by displaying the data according to your question. For example, if you ask to see all the customers from New York, the response would be to display only the records whose state field matches with NY Open an existing query and create new queries You can open an existing query by clicking Queries on the Objects bar and then selecting the query you want to open. You can also create your own queries by clicking New on the Database window. To create a new query, you can use the Simple Query Wizard, which will bring you through the selections you want for your query. Sample Query Datasheet view Selecting fields to include in a query You can create a query that will display only selected fields from a table instead of displaying all fields. In the Simple Query Wizard dialog box, select which fields you want included in the query. Move all the fields into the Selected Fields box Move the fields one at a time Remove fields out of the Selected Fields box by pressing one of the remove buttons If you wanted to select all the fields except one, you can move them all to the selected fields list and then remove the one field you don't want. Once you have made your selections, press Next to move to the next dialog box in the Wizard. The Simple Query Wizard Create an Access form A form allows you to view your data one record at a time. Forms are useful for maintaining, viewing, and printing records in a database. You can create your own form in the Forms Design window or you can use the Forms Wizard to create a form. The easiest way to create a form is to use the AutoForm Wizard. Use the AutoForm Wizard The AutoForm Wizard uses a table (or query) you select as the basis to create a form that displays all the fields of the table (or query). Once you have created your form, you can view the records one record at a time. The form has a navigation bar just like the navigation bar you have already used in the Table or Query Datasheet view. Access Form View Create, preview, and navigate a report You can create a report, which is a printed version of your data, that is formatted according to your specifications. The data in the report can consist of data from a single table or multiple tables. Access has a Reports Wizard that allows you to easily create a report. The report can be based on a table or it can be based on a query. If the report is based on a query, it will contain the same fields that were selected for the query The Report Preview window Backup and restore a database You may want to create a backup of your data so that if you lose or damage your database, you can recover from the backup. You can use a backup tool, such as the Microsoft backup tool, or some other backup program. To restore the data from the backup, you need to use the same backup tool according to the instructions associated with that tool. Compacting a database It is a good idea to periodically compact and repair a database to recover wasted space created by adding, deleting, and modifying records. Access has a Compact and Repair feature: Open a database Click on Tools and then Options On the Options menu, select Compact on Close. Selecting this option will cause your database to be compacted and repaired every time you close it Setting the Compact on Close option Compacting reduces database storage size Convert an existing database to Access 2003 format It is possible to convert a database created in Access 2000 or 2002 to an Access 2003 database. To convert an Access 2000 or 2002 database to Access 2003 format: Make certain the database to be converted is closed Click Tools on the menu bar, then point to Database Utilities Point to Convert database and choose the format to convert to Enter the name of the database to convert, and a name for the converted database to be stored under Microsoft Office Access 2003 Tutorial 2 – Creating And Maintaining A Database Choose a primary key Choose a field or fields to serve as the primary key for the table. A primary key must uniquely identify each record in the table. Primary keys can consist of more than one field. Primary keys with more than one field are called composite keys Include a common field When one table needs to be related to another table, you must include a common field. The common field will be the primary key in one table. The common field is referred to as a foreign key in the related table. The foreign key in a table can then be used as a primary key to access the record in the related table. Setting field properties When assigning a name to any object in Access, carefully select a name that will indicate what data is stored there. Field properties include their data type, field sizes, and an optional description of the field. When selecting a field size, make sure the size is big enough to hold the largest piece of data that will be stored there. Do not make the field larger then necessary because this will result in wasted disk space Make sure the data type you select for a field is appropriate for the kind of data to be stored in that field. Access field types, slide 1 Access field types, slide 2 Define fields, and specify a table's primary key When you create a table, you name the fields and define the properties for the fields. The table structure is set up and modified in Design View In Design View, you will define each field that will be included in the table When all the fields have been defined, you will then specify which field(s) will be the primary key. The primary key is not mandatory, but it is a good idea to assign one The database Design View window Choosing a primary key Click a row selector for the field you want to use as the primary key, and then click the Primary Key button on the toolbar. After clicking the Primary Key button, a key symbol appears in the row selector to indicate the key field. Add records to a table using Datasheet View Once the table has been created, you can then add records to the table using Datasheet View. As you enter records, they will be placed in the order in which you enter them. However, when you close the table and open it again, the records will be ordered according to the primary key order. The navigation bar at the bottom of the Datasheet view will indicate how many records are in the table and what the current record is (i.e., the record on which your cursor currently rests). You can move through the fields in the table by pressing the Tab key. Once your cursor is moved off a record, that record is automatically saved on your disk. Datasheet View with 2 records added Modify the structure of a table by deleting, moving, and adding fields The structure of a table can be modified after it has been created. To delete a field, enter Design View, right-click on the field, and then click Delete Rows on the drop down menu. To move a field, (you also do this in Design View) click on the field you want to move, and while holding your mouse button down, move the field to the desired location. To add a field in Design View, right-click the field where you want to insert the new field and then click Insert Rows on the dropdown menu. Moving a field in Design View Adding a new field in Design View 1. Right-click the row selector for the field you want to insert the new field in front of--StartDate in this figure. 2. Select Insert Rows from the shortcut menu, and a new, blank row will be inserted before the row you selected, as shown below. 3. Enter the information for the new field. Change field properties You can make additional modifications to the structure of a table by changing the properties of the table's fields. For example, if you have a field that represents a currency value but you do not want to display dollar signs, you could change the format to a standard format In the Design View, you will find a list of all formats available to you. You can make a selection from the list of options Each data type has a separate set of options available in the Field Properties portion of the Table Design Window Field properties are changed in the Design View window. Changing field properties in Design View Copy records from another Access database If the data you want in your database already exists in another Access database, you can copy the records from that database into your database. You can use cut and paste to do this: Open the database that contains the records you want to copy Select the records you want to copy and then press the Copy button. This places the records onto the Windows clipboard Open the database to which you want to copy the records and open the desired table to receive the copied records Place your cursor on the next available row in the table and press the Paste button Import a table from another Access database You can also import an entire table, including its structure, into another database. To import a database table: Click the File menu Point to Get External Data, and then Import Locate and select the database and the table you want to import This differs from the cut and paste method because you actually import the entire table, its structure, and its data. The Import Objects dialog box Copy and import considerations If you choose to copy records from one table to another, it is very important that you first determine that the two tables have the exact same data structure. If the two data structures differ in any way, the copy will cause an error When you import, you are importing an entire table, including its data and its structure. This is a good way to include a table in your database that was previously designed in a different database Delete and change records Once records have been added to a table, they can be deleted or modified: To change or modify a record: In Datasheet view, click the row selector for the record(s) you want to delete and then click the Delete Record button on the toolbar Place your cursor on the record and then on the field you want to change You can then edit the field's value as you wish by typing in new data You can switch from navigation mode to editing mode depending on what you want to do at the time. When you are editing a record, you are in editing mode, Otherwise you are in navigation mode Editing mode is indicated by a pencil symbol in the left margin of the datasheet view An alternate method for deleting a record Microsoft Office Access 2003 Tutorial 3 – Querying a Database Learn how to use the Query window in Design view The Query window in Design view allows you to specify the results you want for a query. In the query Design view, you can specify which fields you want to be included in your query results. You can also control what records are displayed in the query by specifying select query criteria. Each column in the design grid represents a field that will be used in the query. You can run the query at anytime to view the results according to the current specifications. Add fields to a query in Design view The design grid is used to specify the fields and records you want to see. Add fields to the design grid by double-clicking the field in the field list or by dragging the field to the design grid. Remember that the results of a query provide a temporary view of the data The contents displayed in a query are a result of the fields you select and the criteria you specify in the query design grid When you use the query design window, you use Query By Example (QBE). When you use QBE, you give Access an example of the information you wish to see when you run your query. The Query Design view window Create, run, and save queries From the fields list, either drag or double-click fields that you want included in the query. A query result differs from a table's datasheet view in that only selected fields are displayed If you move a field to the design grid and then you want to remove it, you can click on the field's column and then press the delete key. The results of the query will be displayed in order by the primary key of the table unless you specify another sort order. You can save the query and give it a name by pressing the save button on the toolbar. Selecting, displaying and sorting fields A sample query datasheet Update data using a query You can use the query datasheet to update data in a table. It is important to realize that the query datasheet is a temporary view of the data. However, when you update data by means of the query datasheet, the updates are placed directly into the underlying table. You can only update fields that are represented in the query. To observe the actual changes made to the table, close the query and open the table in datasheet view. Access is a relational database A database is almost always a collection of tables. Access is a relational database management system that allows you to form relationships between the tables. When you form a relationship between tables, you are joining the tables. Tables are joined on common fields between the tables. When tables are joined, you can view data from both tables as if the tables were one combined table. A one-to-many relationship Tables can be joined in three ways; one-to-one, one-to-many, and many-to-many. A one-to-many relationship exists when one table has many records associated with a given value but the related table has only one record for that value. The table with one record is called the primary table The table with many records is called the related table Queries can be defined to use the relationship to extract data from both tables in a single query. Using referential integrity When dealing with related tables, you need to decide if you want to enforce referential integrity. Referential integrity allows you to maintain the integrity between related tables. The rules associated with referential integrity specify that when you add a record to a related table, there must be a matching record in the primary table. If you choose to enforce referential integrity, you can insure that you will not have orphaned records (records that have no matching record in the primary table). Use cascaded updates and cascaded deletes In addition to referential integrity, you can also tell Access to implement cascaded updates and cascaded deletes. If you choose cascaded updates, making a change in a field that is common to two related tables will cause the update to be made in both tables. Cascade deletes is similar. If you delete a field that is common to two tables, the deletion will take place in both tables. You should carefully consider whether you want to implement these features, as they can have dramatic effects on your data. Selecting the tables for a relationship Setting relationship options The Relationships window Sort data in a query You can control the order of data displayed in a query by altering the queries sort key. Choose a field on which you want the data to be sorted and then specify whether you want the data sorted in ascending or descending order. Specify multiple fields as the sort key if you want to arrange data in sorted order within groups of data. Specify sort criteria for the query in the query design grid. Sort results by data type Sort single or multiple fields Filter data in a query Sometimes you may want to isolate a certain portion of data in your query results. You can set a filter, or a set of restrictions, to specify what records you want to view in the results. Only those records that match the criteria will display in the results datasheet. There are two methods used to make your selections: Filter By Selection or Filter By Form. If you no longer want to view the data with the filter applied you can remove the filter. Using Filter By Selection Specify an exact match condition in a query You can specify an exact match condition, which allows you to specify that only records that match your criteria will be displayed. To specify an exact match, use the criteria row in your query design grid. When you run the query after specifying an exact match, only those records that meet the criteria will be displayed. An exact match condition specifies that the value in the specified field must match the condition exactly. Exact match operators and results Use the And and Or logical operators When you need to use multiple conditions for a query, you can use the logical operators to combine conditions. The And logical operator specifies that both conditions must be met The Or logical operator specifies that one or the other of the conditions must be met When you enter two conditions on the same row of the query design grid, an And condition is created. If you enter two conditions that are on separate rows, an Or condition is created. Illustration of And and Or logic Creating And condition in the design grid Use multiple undo and redo In Access 2003, you can Undo and Redo multiple actions at one time. While working in design view for tables, queries, forms, and reports, you can use the undo recent actions button. The Undo button on the design toolbar has an associated list box. You can open the list box and then select the action you want to undo. If you undo an action and then change your mind, you can also redo actions by the same method, using the Redo button. Using the Undo actions button Perform calculations in a query using calculated fields and expressions Queries can be built to perform a calculation as part of the query. Expressions can be entered into the query design grid. Make certain that you are following the rules of precedence. To perform a calculation in a query, you must add a calculated field to the query design. You have three options for entering expressions: Enter the expression directly into the field text box Enter the expression in the Zoom box Enter the expression in the Expression Builder Create a form using the Form Wizard You can create a form from scratch or you can create a form using the Form Wizard. The Form Wizard will lead you through a series of choices to help you develop the form based on a table or a query. You will need to select the type of layout you want for your form, the style of the form, and a name for the form. After you have selected the table or query on which the form will be based, you will select which field(s) will be used on the form. Open the Form Wizard dialog box Use Form Wizard to choose a form layout Use Form Wizard to select a style for the form Completed Form Change a form's AutoFormat You may want to change the appearance of a form after it has been created with the Form Wizard. Clicking on the AutoFormat button and then make your selection. Click the button beside each format to view a sample of that particular format. Once you have decided on a format, click OK. A completed form created with the Form Wizard The AutoFormat dialog box Find data using a form You can navigate through all the records in a form, but you may want to find a particular record more quickly. The Find command allows you to specify the record you want to see and then will navigate directly to that record. To use the Find command: Place your cursor in the form on the field for which you want to search Press the Find button and enter the value you are looking for The form will display the record(s) that match your Find criteria. Setting up a Find operation Using wildcard characters in a Find Maintain table data using a form Not only can you view your data in a form, you can also make modifications to the data right in the form. Once you have navigated to the record you want to change, you can make your changes. When you move off the record, the changes are made directly to the table. Access will allow you to add, modify, and delete records in forms view. A form in editing mode Add and Delete records in Form view In addition to making changes to a record in the form, you can also delete an entire record. The deletion is made immediately and you will not be able to recover that record once it is deleted Always approach deletions of any kind with caution Records can be added using a form as well. To add a record: Click the New Record button on the form view toolbar A blank form will appear. Enter the new data values for the new record Create a form with a main form and a subform You can create a form with a subform on two tables that have an established relationship. When the relationship between the tables is a one-to-many relationship, the main form will consist of data from the primary table and the subform will consist of data from the related table. By selecting two related tables in the Form Wizard, you can produce a form with a subform. The form with subform is a great way to display data for tables that have a one-tomany relationship. Form Wizard Form/Subform dialog box Form and subform data Notice in the following figure that the main form contains information about the employer whose ID is 10122. The data in the subform are positions that this particular employer has available. Also notice that you have two sets of navigation buttons. You can navigate the data for either form. The outer navigation buttons apply to the main form The inner navigation buttons apply to the subform An example of a Form with subform Create a report using the Report Wizard You can easily create a formatted printout of data in table(s) in a database by using the Report Wizard. The Report Wizard will ask you a series of questions to help you format the report. Once the report has been created, either with the Report Wizard or your own design, you can change the design later. You will find that the choices you make in the Report Wizard are similar to the choices in the Form Wizard. Choices include grouping and sorting options, as well as report layout options. You can preview the report to view how it will look when printed.