COMM335 Summer 2016 (Tutorial 1) (1) Creating Tables in a Database

Transcription

1 COMM335 Summer 2016 (Tutorial 1) (1) Creating Tables in a Database The purpose of this tutorial is to enable you to create tables in a database, set the primary key for a table, add fields and specify field properties in Microsoft Access. You will create a simple database to keep track of the customer and reservation information in a video store using Microsoft Access. For the purpose of this tutorial, we assume that there are three tables in the database as follows: tblcustomer tblreservation tblvideo The fields for the above tables are shown below: tblcustomer Field Name Description (Optional) Data Type Field Size Format MemberNo Unique Identifier for Customer (PK) AutoNumber Long Integer LName Last Name Text 50 FName First Name Text 50 Gender Gender Text 1 DateJoin Date Joined Date/Time Short Date VIP VIP Yes/No Yes/No tblvideo Field Name Description (Optional) Data Type Field Size Format VideoNo Unique Identifier for Video (PK) Text 20 MovieTitle Movie Title Text 50 Format Format, e.g. VHS, DVD Text 10 NoOfCopies Number of Copies in Store Number Integer Fee Rental Fee Currency Currency tblreservation Field Name Description (Optional) Data Type Field Size Format MemberNo Member No (PK) Number Long Integer VideoNo Video No Text 20 DateReserve Date of Reservation Date/Time Short Date Note: The primary keys are underlined. A table has ONLY ONE primary key but a primary key may consist of more than one field. COM335 Summer 2016 Tutorial 1 Page 1

2 Ø Creating Tables Demonstration: Creating the Customer Table. a. Launch the Microsoft Access and create a new database named Reservation.accdb. b. Switch to Design View and create a table for Customers. Save the Table as tblcustomer (tbl is the prefix for table name. This is not mandatory but is regarded as best practice). Design View icon c. Add fields and set data types, field properties, and descriptions as follows: i. Add a field: MemberNo (to replace the ID field) o Data type: AutoNumber o Field size: Long Integer (set automatically) Default field size for AutoNumber AutoNumber: The value of this field is assigned by ACCESS automatically and consecutively. It is unique for each record, and thus is frequently used as the primary key for simplicity. In case there is already a unique field in a table such as Student Number, this AutoNumber field is not necessary. COM335 Summer 2016 Tutorial 1 Page 2

3 Practice: ii. Add a field: LName o Data type: Text o Field Size: 50 o Format: > (To learn more about Format, press F1 for Help.) o Caption: Last Name iii. Add a field: FName o Data type: Text o Field Size: 50 o Caption: First Name iv. Add a field: Gender o Data type: Text o Field Size: 1 o Format: > o Caption: Gender o Validation Rule: M or F o Validation Text: Please input M or F. v. Add a field: DateJoin o Data type: Date/Time o Format: Short Date (To learn more about other date format, press F1 for Help.) o Caption: Date Joined vi. Add a field: VIP o Data type: Yes/No o Format: Yes/No (set automatically) o Default Value: No d. Set Primary key (choose a field à click the Primary Key icon on the ribbon under Design tab.) e. Switch to Datasheet View and input some test data to the tblcustomer table. What values are entered in the MemberNo field? f. Input some invalid values in the Gender and DateJoin fields. Does the validation work? Create the Video table (tblvideo) and the Reservation table (tblreservation). o Add the fields to these two tables as shown on page 1. o Remember to choose appropriate data types and field properties. o For tblvideo table, make sure that the number of copies and rental fee are not negative, i.e. the value input is greater than or equal to 0. (Which operator should be used in the validation rule?) o For tblreservation table, set the default value of the Date of Reservation field to today s date. (Hint: Use the system function, Date( ), to get the system date.) COM335 Summer 2016 Tutorial 1 Page 3

4 Questions: 1. How to set the primary key consisting of two fields (e.g. MemberNo and VideoNo in the table tblreservation)? 2. Can we use AutoNumber as the data type for the MemberNo field in the table tblreservation? Why? If not, what data type should be used? 3. What is the difference between Integer and Long Integer? What field size should be used if a Number field contains non-integer values? COM335 Summer 2016 Tutorial 1 Page 4

5 (2) Creating Relationships and Importing Data The purpose of this tutorial is to enable you to: 1) create relationships among tables in Access; 2) print table definition and relationship report; and 3) import Excel data to Access tables. You should download the sample database, comm335_t2.accdb, from the UBC Connect as the foundation to create table relationships and import data in this tutorial. There are four tables in the database, viz. tblcustomer, tblmovie, tblvideo and tblreservation. Your first task is to create the relationships among these four tables as follows: Ø Creating Relationships Demonstration: Create a one-to-many relationship between the tblcustomer and tblreservation tables. Key Steps: a. Make sure all tables are closed. b. Select Database Tools à Relationships. Click Show Table if the Show Table dialog box does not pop up automatically. c. Add the four tables to the Relationships window and close the Show Table dialog box. (What are the primary keys and foreign keys of these tables?) Primary Key: a field (or combination of fields) that uniquely identifies each record. Foreign Key: a field which is the primary key of another related table (parent table). COM335 Summer 2016 Tutorial 1 Page 5

6 Key Steps (cont d): d. Select the primary key (MemberNo) of the tblcustomer table, drag it to the corresponding foreign key (MemberNo) in the tblreservation table, and release your mouse. The Edit Relationships dialog box pops up. e. Check the Enforce Referential Integrity, Cascade Update Related Fields and Cascade Delete Related Records boxes. Click Create. Referential Integrity: the enforcement of referential integrity will prevent the deletion of a record or the change of the primary key in the parent table (tblcustomer) if there is a corresponding record in the child table (tblreservation). Practice: Create the relationship between the tblmovie and tblvideo tables. Create the relationship between the tblvideo and tblreservation tables. Test the Referential Integrity, e.g. o Add a record in the tblcustomer table and add a record in the tblreservation table for this customer with a random Video No. Does it work? Questions: 1. What does Cascade Update Related Fields mean? 2. What does Cascade Delete Related Records mean? COM335 Summer 2016 Tutorial 1 Page 6

7 Ø Reporting Your Work Demonstration: Printing Table Definition. Key Steps: a. Select Database Tools à DatabaseDocumenter. The Documenter window opens. b. Select All tables and click the Options button. c. The Print Table Definition window opens. d. Select Properties and Relationships for Tables, Name, Data Types, and Sizes for Fields; and Nothing for Indexes. Click OK. e. Click OK. The Print Preview window opens. (You don t need to print this report in the lab.) Printing the Relationship Report. Key Steps: a. Select Database Tools à Relationships. b. Select Relationship Report on the ribbon. c. Select Landscape in Print Preview window. d. Click Print (You don t need to print this report in the lab.) COM335 Summer 2016 Tutorial 1 Page 7

8 Ø Importing Data from an Excel file You can import data from external sources such as a database file, an Excel spreadsheet, a delimited text file or a fixed-width text file. Before you proceed to import data from an Excel file, make sure that the data in each worksheet is arranged in an appropriate tabular format, and it has the same field (column) names as those in the table. Demonstration: Download movie_t2.xlsx from the UBC Connect. Import the Customer data from the movie_t2.xlsx to the tblcustomer table in the database. Key Steps: a. Select External Data à Excel. The Get External Data window opens. b. Select the Excel file movie_t2.xlsx to import. c. Select Append a copy of the records to the table and select the tblcustomer table in the dropdown box. Click OK. d. Select the Customer worksheet. Click Next. e. Check First Row Contains Column Headings. Click Next. COM335 Summer 2016 Tutorial 1 Page 8

9 Key Steps: f. Click Finish and then Close. (Note: All field names in a table should EXACTLY match with those in the Excel file.) Practice: Import the Reservation data from the movie_t2.xlsx to the tblreservation table. Question: Member No Video No Date Reserve /31/ Does it matter 7 which table(s) 15 should 01/31/2012 be imported first? Why? - End of document - COM335 Summer 2016 Tutorial 1 Page 9