COMM 391 Winter 2014 Term 1

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1 COMM 391 Winter 2014 Term 1 Tutorial 3: Microsoft Access Introducing Tables, Relationships, and Creating Queries The purpose of this tutorial is enable you to 1) explore the tables and relationships in Access database; and 2) create queries using Query Wizard and specify simple query criteria. You should download the sample database, c391_access_t3.accdb, from the UBC Connect as the foundation to create queries in this tutorial. Understanding Database Fundamentals A database is a collection of data organized as meaningful information that can be accessed, managed, stored, queried, sorted, and reported. Data is what is entered into a database while information is the finished product that is produced by the database. A database management system (RDBMS) is a software system that provides the tools needed to create, maintain, and use a database. Microsoft Access is an example of RDBMS. The foundation of every relational database is a table where data, such as customer s name, product s description, etc. is stored. Tables organize data into columns and rows. Columns display a field, the smallest data element of a table. Each row in a table contains a record. Each record contains multiple fields. Exploring Access Views Access provides two different ways to view a table: the Datasheet view and the Design view. The Datasheet view is a grid containing fields (columns) and records (rows), similar to an Excel spreadsheet. You can view, add, edit and delete records in the Datasheet view. The Design view gives you a detailed view of the table s structure and is used to create and modify a table s design by specifying the fields it will contain, the field s data types, and their associated properties. The data types define the type of data that will be stored in a field, such as text, number, date/time, currency, etc. The field properties define the characteristics of the fields in more details. For example, for the DateJoin field in the customer table, you could set a field property that requires a Short Date format. Designer View Datasheet View COMM 391 Winter 2014 Term 1 Tutorial 3 Page 1

2 Demonstration: Switch between the Datasheet view and the Design view of the Customer table. Key Steps: a. Open the Customer table (tblcustomer). b. Click the Home tab and click View in the Views group to toggle between the current view and the previous view. c. Click the Home tab and click View arrow in the Views group, and then select the view you want to use. d. Right-click the table (tblcustomer) tab and select the view you want to use. e. Right-click the table in the Navigation Pane and select the view you want to use. f. Click one of the view shortcuts in the lower-right corner of the Access window. g. Use the Navigation bar to go to Next Record, and then Last Record. h. Use the Search box to locate a customer, e.g. Susan. What do you see? i. Add a new customer record using any name. Click the record selector to save the record. Are there any other ways to save the record? j. Sort the customer records in ascending order of Last Name. Can you sort the records by Last Name and First Name? Question: Do you think you will let the users open the Customer table and view, add and edit the customer records? COMM 391 Winter 2014 Term 1 Tutorial 3 Page 2

3 Understanding Relationships Microsoft Access has the ability to create relationship between two tables, whereas Excel cannot. When relational databases are designed properly, users can easily combine data from multiple tables to create queries, forms and reports. Relationships are created in the Relationships window after the database tables are created. The most common method of connecting two tables is to connect the primary key from one table to the foreign key of another. For example, the MovieNo (primary key) in the Movie table is joined to the MovieNo (foreign key) in the Video table. One Movie has Many Video (formats). primary key foreign key Remember, a primary key is a field that uniquely identifies each record in a table. A foreign key is a field in a table (Child table) and it is also the primary key of another table (Parent table). Question: Refer to the diagram above, which one is the Parent table and which one is the Child table? tblmovie is the table and tblvideo is the table. Referential Integrity When a relationship is created, we can select to enforce the referential integrity. When enforce referential integrity is checked, Access ensures that data cannot be entered into a related table unless it first exists in the primary (parent) table. COMM 391 Winter 2014 Term 1 Tutorial 3 Page 3

4 For example, we cannot enter a new reservation into the Reservation table using a MemberNo that does not exist in the Customer table. This rule ensures the integrity of the data in the database and improves overall data accuracy. Referential integrity also prohibits users from deleting a record in one table if it has records in related tables. Can you give an example? Demonstration: Key Steps: k. Open the database. l. Click Database Tools tab and click Relationships in the Relationships group. The Relationships window opens. Can you explain the relationships among these four tables shown in the diagram above? m. Test the Referential Integrity, e.g. Add a record in the tblreservation table using a random MemberNo that doesn t exist in the tblcustomer table. What is the error message? Delete a customer record from the tblcustomer table when the customer has made a reservation for a video, i.e. the MemberNo exists in one of the reservation records in the tblreservation table. What is the error message? Question: Why is Referential Integrity important in a database? COMM 391 Winter 2014 Term 1 Tutorial 3 Page 4

5 Creating Simple Queries Queries allow you to select specific records from a table (or from several tables) and show some or all fields for the selected records. The displayed records may appear in a different sequence from the underlying table. You may create a query either by using the Query Wizard or specifying the tables and fields directly in the Query Design View. Specify sorting sequence. By default, the records are listed in primary key sequence. Selected fields that will be displayed in the query result, i.e. dataset. Specify the selection criteria. The Query Design view consists of two parts. The top portion contains tables with their respective field names. If a query contains more than one table, the join lines between tables will be displayed as they are created in the Relationships window. The bottom portion (known as the query design grid) contains columns and rows. Each field in the query has its own column and contains multiple rows. The rows permit you to control the query results. The Field row displays the field name. The Table row displays the data source. The Sort row enables you to sort in ascending or descending order. The Show row controls whether the field will be displayed in the query results. The Criteria row is used to set the rules that determine which records will be selected, e.g. a list of movies with video in DVD format. The results of the query are shown in Datasheet view. Demonstration 1) Create a query using Query Wizard to list all the movies in the database, sorted by title. (qrymovie) Key Steps: a. Click the Create tab and click Query Wizard in the Queries group. b. Select the Simple Query Wizard in the New Query dialog box. COMM 391 Winter 2014 Term 1 Tutorial 3 Page 5

6 Key Steps: c. Select tblmovie table in the Query Wizard dialog box. d. Select the fields and add them to the Selected Fields list box using the directional arrows. e. Choose the Detail query to show every field of every record in the result. f. Enter the name of the query, qrymovie. g. Open the query to view information. h. Switch to Query Design view. i. Select to sort the query result in ascending order of title. How do you create this query without using Query Wizard? COMM 391 Winter 2014 Term 1 Tutorial 3 Page 6

7 Demonstration: 2) Create a query to list the title, length, and synopsis of all movies with the Rating equal to PG. Sort the result by Title. (qrymovierating) 3) Create a query to list the title, length, and synopsis of all movies that are categorized as A or B. (qrymoviecatab) 4) Create a query to list the title, length, and synopsis of all movies that have DVD format. Sort the result by Title. Do not display the format field. (qryvideodvd) Practice: 1) Create a query to list the movie title, category code, and synopsis of all movies of which length is greater than 120 minutes and rating is PG. Sort the result by title. (qrymoviepg) Write down the criteria: 2) Create a query to list the movie title, length, synopsis, and format of those videos that have at least 3 copies. (qryvideo3copies) Write down the criteria: 3) Create a query to list the video rentals that are two weeks overdue. The list should include the customer name (last name and first name), customer s phone number, movie title, video format, the date the video is rented out and the due date. (qryrentaloverdue) Write down the criteria: - End of document - COMM 391 Winter 2014 Term 1 Tutorial 3 Page 7