DATABASE DESIGN USING MICROSOFT ACCESS

What is a Database?  DMS Database management system  Database Collection of data organized in a manner that allows access, retrieval, and use of that data. --- OR --- A place to store data and retrieve information

DATABASE DESIGN USING ACCESS 2007

ACCESS OBJECTS… Like Excel Enter, edit, and delete data Display, sort and filter Tables Ask questions and get answers from data Queries Visual Can limit data by user Forms Print customized displays of data Reports

 Each row is a separate record, or an entry in the database  One customer  One order  Each record has a unique identifier, called a primary key, such as:  Customer ID  Student ID  SSN  Each column is a field  Name, address, phone number  Item number, quantity ordered TABLES Primary key field

THE KEY To designing a good database …. A good plan

NORMALIZING DATA Table designs should eliminate redundant (repeating) data. This is called normalizing a database.  Customer names and addresses should be listed in a separate table, and not included with every order the customer makes  Students’ names and address are in a separate table, and not included with their schedule and grade information More info on database design for Access 2007 is available here.here

STEPS FOR DESIGNING TABLES What tables? An online clothing store might include:  Product inventory Item number, Item name, purchase price, number in stock  Vendors (the people you buy from) Vendor number, vendor name, address, city, state, zip, terms  Customers (the people you sell to) Customer number, customer, name, address, city, state, zip, phone number  Orders Customer number, item number, quantity

STEPS FOR DESIGNING TABLES  Choose a primary key for each table  Format the data for each field  Text or numbers  Maximum number of characters  Required or not?  Security – who will have access?  Set relationships between tables

COMMON ACCESS DATA TYPES May contain letters, numbers, and symbols Maximum 255 characters Cannot be used for calculations Text fields (default) May contains ONLY numbers Can be positive or negative Can be used for calculations Number fields May contain ONLY monetary data Will display like currency formatting in Excel Can be used for calculations Currency fields

NUMBER FIELDS BByte: Integer from 0 to 255 IInteger: Integers from -32,768 to 32,767 LLong Integer: Integers from -2,147,483,648 to 2,147,483,647. SSingle: Numbers with up to 7 decimal places DDouble: More decimal places; 2x the storageDecimal: More decimal places; 3x the storage RReplication ID: Special identifier required for replication Choose the smallest size you can for your data

OTHER ACCESS DATA TYPES  Memo  Up to 63,999 characters  Date/Time  AutoNumber  Stores a unique sequential number for each record  Values CANNOT be re-used  Yes/No  Values can be Yes/No, True/False, or On/Off  OLE Object  Hyperlink  Attachment  Images, spreadsheets, etc.

RELATIONSHIPS  Relationships exists between tables  One-to-many (most common)  Each customer has many orders  Each student has many classes  Each employee has many paychecks  One-to-one  Each customer has one address  Each student has one locker  Each employee works for one department  Many-to-many (least common)

FACTS ABOUT ACCESS 2007  Field names  Can have up to 64 characters  Can contain letters, numbers, characters and spaces EXCEPT Periods (.) Exclamation points (!) Accent graves (`) Square brackets ([ and ])

USING ACCESS Some things about Access are different from other Office applications  All tables, queries, forms and reports are stored in the same file  When you start a new database, you have to name it before you can create any tables  Access saves database files with an.accdb extension  When you enter data, each record is automatically saved when you move to the next  If you delete a record or a table field, it gone for good (older versions).

THE ACCESS WINDOW