Guest Author - Chris Curtis
We encounter many databases throughout our lives. Even people who have relative little access to a computer, still encounter several databases. For example, whenever you are in contact with the bank about your account, that information is contained in a database system. If you call 411 to get a telephone number, you are dialing into a database. When you buy groceries at the supermarket, the transaction is scanned into a database. Records about all kinds of information are held in database systems.
MS Access is an end-user database software. In and of itself, Access is not a database, but rather a tool that allows the user to design and develop their own database for their specific purpose. It contains a variety of tools that you can use to sort, manipulate, extract, and summarize data to satisfy your informational needs. The database you create can be simplistic or complex depending on the amount and type of information that you need to manage.
Information stored in an Access database is organized in structured rows and columns whereby the columns represent fields such as a zip code field in an address database and rows represent a single person's record. Here is a list of terms commonly found in an Access database.
Database – is a collection of information that is managed in a systemized program. Basically it is a set of facts about related information. Databases can be flat or relational.
Flat Database is a simple list stored in a single Access table or in an Excel worksheet, i.e., a list of all of your passwords and pin numbers.
Relational Database is a collection of tables that are designed to work together in managing information that is closely related. With a relational database, you would have multiple tables to store like data with the ability to link tables through common information. For example, you might have an extensive media collection that includes DVDs, VCR Tapes, CDs, Books, MP3s, Digital Photos and Digital Videos. You want to be able to store information about each type of media including artists/actors, authors, subjects, copy right dates, dates of purchase, costs etc. You might want to be able to extract data to show you all the media you have on a particular artist. For example, suppose you have several CDs, MP3, original photos and DVDs featuring Alison Krauss and the Union Station with Jerry Douglas. You could extract a list of the entire collection using Alison Krauss as the common thread even when the data is stored in several different tables.
Table is the Access object (or container) where the collection of data is stored.
Record is the set of data stored in a table row about a single person or thing such as the information about the milk you are buying at the store. The record would likely contain:
• product category – Milk,
• brand – Garelick,
• quantity – ½ gallon,
• price - $2.89
Field is the category of data store in a table column pertaining to all of the records in the table. A field would contain all the brands sold by the supermarket.
Data Value is one piece of information contained in a single record. i.e., Garelick
Primary Key is a field that uniquely identifies each record in a database table. i.e., Social Security number
Query – a question used to extract specific data that meets the criteria specified in the query. You may want to locate all the customers that use a certain accountant. The criteria would be the accountant name. The query would generate a list of the customers linked to the criteria specified.