Microsoft Access 2003 - Intro

Class 2Designing Databases and Tables

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Naming Conventions Clearly defines the type and purpose of each

object A consistent naming convention will

Bring order to your database Aid in documentation Make it easier to understand the database (ie: choosing

an object using the report wizard, reading a report generated by the Database Documenter)

Common naming conventions (choose one and then be consistent) Hungarian Reddick (http://www.xoc.net/standards/) Leszynski – Popular

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Naming Conventions (cont’d)

Access Requirements Object names

• up to 64 characters long• Can include any combination of letters, numbers, spaces, and

special characters, except a period (.), and exclamation point (!), and accent grave and brackets ([])

• Cannot begin with a space• Cannot include control characters (ASCII values 0 through 31)

Table, view, or stored procedure names cannot include a double quotation mark (“)

Table and Query names must be unique in the database. Naming any other objects with the same name is NOT recommended

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Creating a Table in Design View In Database window, double-click the

option to create a new table using Design View Type desired field names in appropriate

column Choose data type for each field Type description for each field (optional)

Mark primary key (right-click desired field) Set field properties, if desired Save table

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Data TypesData Type Description

Text Includes any characters up to a maximum of 255 characters (determined by field size). If the data includes a mix of numbers and any amount of letters, choose Text. (The default data type is Text).

Memo Use this data types when Text is not large enough. Like Text, this data type can also have letters and umbers, but can be much larger – up to a little over 64,000 characters.

Number Includes various forms of numerical data that can be used in calculations.

Date/Time Date and time entries in formats showing date, time, or both.

Currency Use for currency values with up to fours digits after the decimal place. This data type is more accurate for large numbers than the Number data type, but generally takes up more space.

AutoNumber Usually this is used to create an identification number for each record. The value for each record increases by one.

Yes/No Only two possible values can be in this field. Options include Yes/No, True/False, On/Off. The default style shows a check box with a checkmark on for Yes, or a blank for No.

OLE Object This data type allows you to place another file type into your record. Within the field you could insert a picture (a company logo, for example), a Word document (employee resume), or an Excel spreadsheet (client summary chart).

Hyperlink This allows you to insert a Web address such as www.durhamcollege.com, which will launch when you click it in Datasheet view or on a form. You could also type a path and file name to a file on your hard drive (C:\docs\myres.doc) or a network drive.

Lookup Wizard Creates a lookup column, which creates a list of values from which to choose when entering data.

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Field Properties Field Properties

• Field Size• Format• New Value (new in Access 2000)

• Precision (new in Access 2000)

• Scale• Decimal Place• Input Mask• Caption• Default Value• Required• Allow Zero Length• Indexed• Unicode Compression (New in Access 2000 – stores characters in two

bytes mainly to accommodate language fonts)

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Field PropertiesField Size for Text data types determines the maximum number of characters you can type. For Number data types, the Field Size property can be used to determine how large the number can be and if you can have decimal places.  

Number Type Description

Byte Stores numbers from 0 to 255 (no fractions).

Long Integer (Default) Stores numbers from –2,147,483,648 to 2,147,483,647 (no fractions).

Integer Stores numbers from –32,768 to 32,767 (no fractions).

Single Stores numbers from–3.402823E38 to–1.401298E–45 for negative values and from1.401298E–45 to 3.402823E38 for positive values.

Double Stores numbers from–1.79769313486231E308 to–4.94065645841247E–324 for negative values and from 1.79769313486231E308 to 4.94065645841247E–324 for positive values.

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Field Properties (cont’d)

Format Used especially for Date/Time data types – how you want the values displayed.You can also type codes in the Format property box. For example, type m/d/yyyyfor a date type to display 1/1/2000.

Caption This will appear at the top of the column in Datasheet view. Captions will automatically carry through to new forms and reports instead of the field name. Here, you can include spaces, and other punctuation marks not normally allowed in the field name.

Default Value This will appear in new records entered in the table.

Input Mask A template to validate how each character is entered into the field.

Validation Rule Allows you to verify data as the user enters it into the table.

Validation Text Appears in a dialog box when a Validation Rule is broken.

Required The user has to fill in this field before going to another record.

Allow Zero Length

You can use the AllowZeroLength property to specify whether a zero-length string (" ") is a valid entry in a table field. Note:   The AllowZeroLength property applies only to Text, Memo, and Hyperlink table fields.

Indexed Makes searches and sorts on this field go quicker.

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Indexes Index

A separate hidden table that consists of pointers to records or a group of records

Automatically set on primary keys Makes sorting and searching more efficient Maximum of 32 per table Normally index any field you plan to sort on or

search by frequently Can be added at any point in the development

of the database to improve performance

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Formatting Tables When in Doubt, Right-Click

Insert/Delete Fields or Records Hide/Unhide, Freeze/Unfreeze

Right-click the field name or the record selector and choose the desired option from the pop-up menu

Change column width/row height Position mouse pointer on line between

field names or rows and drag or double-click

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Formatting Tables (cont’d)

Move/Rearrange Fields• Click once on field name, then drag field

name until a black line is visible and drag to new position

Formatting Fields• Font and style changes made to a range of

data will affect all data in the ENTIRE table• Remember, tables are meant to store the

RAW data – to make data pretty, put it in a report!

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