In-Depth Guide – Database Basics Creating and Populating

In-Depth Guide ? Database Basics Creating and Populating

Learning Objectives

By reading and completing the activities in this chapter, you will be able to: Given a database logical schema, create a database in Microsoft Access, including o Creating tables, fields and primary key o Establishing relationships between tables Add records to a table

Chapter Outline

Introduction Creating a database Creating tables Creating relationships Populating tables with data Summary

Introduction

In this chapter, we will help you learn how to create and populate a database using Microsoft Access. While most of you will probably never create large databases as a major part of your jobs, it is useful to know how to create small databases. As discussed in Chapter 5, using a database management system (such as Access) to store some types of data can be very useful. As a result, being able to create simple databases may be a handy skill in the future. Fortunately, personal-level database management systems, such as Access, make it relatively easy to create a database.

Once you have a good database design, there are a few key things you need to be able to do when creating a database. You need to be able to:

Create tables Create fields within tables Choose the proper data type for each field (for example, text, numeric or date/time) Establish relationships between tables

Once the database is created, you will also need to know how to add records to the tables that make up the database.

We will use the "Wish-List" database from Chapter 5 to illustrate how to accomplish all of these tasks. The schema (design) of the database is shown in Figure 1.

Figure 1 - Wish-List Database Schema

Creating a Database in Access

In this section, we give you step-by-step instructions for creating and populating the Wish-List database. The first step (once you have a good design) is to give the database a name. This effectively creates an empty container for the database. Access stores all database elements, including the data in a single file on your computer. In Access 2007, this file as an .accdb file extension.

To create the database file, simply start Access then click on "Blank Database" in the Access Getting Started screen, as shown in Figure 2.

Figure 2 - Access Getting Started Screen One of the most important aspects of creating a new, blank Access database is knowing where it will be stored. You should make it a habit to click on the folder icon in the lower right-hand corner of the opening Access screen. This allows you to specify the location in which the database file will be stored. Also be sure to give the database a meaningful name. These steps will help you locate the database in the future. The relevant opening Access screen is shown in Figure 3. Once you have created the database file, you can start creating tables.

Figure 3 - Specifying the Database Name and Location

Creating Tables

Creating tables in Access is not difficult if you have a good data model. To create a table, select the Create ribbon, then Design View, as shown in Figure 4. Typically with a new database, Access takes you directly to the Table Tools ribbon, from which you can simply choose the Design View. When you do so, Access brings up the Save As dialog box, which allows you to specify the name for your table.

Figure 4 - Creating a Table Selecting the Design View takes you to a form for adding the fields that make up your table, as shown in Figure 5. Enter the name of the field in the "Field Name" column of the form. While Access allows spaces in field names, it is generally a bad idea to do so. So, we recommend avoiding spaces. When a field name is made up of more than one word, capitalizing the first letter in each word (as in FirstName) makes the field name easier to read.

Figure 5 - Entering Table Information

In addition to the Field Name for each field, you will also need to select the data type, which specifies what sort of data can be stored in each field. Access' data types are listed and briefly described in Table 1. Data types generally have additional properties that can be set. Discussing these in detail is beyond our scope. However, there is one property we want to mention. For text fields, you should set a reasonable field size rather than the default of 255 characters, which is the maximum. For example, you probably do not need 255 characters for the FirstName field. See for more information about field properties.

Data Type Text Memo Number

Date/Time

Currency Autonumber

Yes/No OLE Object

Hyperlink Attachment

Description Relatively short (up to 255 characters) alphanumeric values. Long blocks of text. Allows more than 255 characters. Numeric values. There are several different variations of the number data type, including integer (from -32,768 to 32,767), long integer, dingle and double precision. Time-based data, including dates and times. The data can be displayed in several different formats. Monetary values. A number that is automatically generated for each record in a table. The numbers are stored as integer values. The only purpose of an autonumber field is to make a record unique. Boolean values such as true/false, yes/no and on/off. External objects that conform to the OLE standard. Microsoft recommends using the Attachment data type, which is less restrictive than OLE Object. Links to email addresses, websites, etc.

Files such as images and audio. You can attach multiple files to a single record.

Table 1 - Access Data Types

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