What can you do with a database?
The purpose of a database management program is to organize and manipulate data. Using a database program, information can be stored for easy retrieval and sorted in any order. Specific information can be located quickly.
For example, you might want to create a database file to store the
birthdates
of the students in your class. You would need to record the name and
birthdate
for each child, so these become your fields. You might even want to
store
the first and last names in separate fields. You database would then
look
something like this:
|
|
First Name | Last Name | Birthdate |
|---|---|---|---|
| a record--> | Juan | Gomez | May 21 |
| a record--> | Susan | Smith | April 13 |
| a record--> | LaShondra | Johnson | January 25 |
| a record--> | Maria | Harrison | November 30 |
| a record--> | Keeshon | Washington | December 18 |
| a record--> | Maria | Zariya | February 28 |
| a record--> | Jesus | Modoa | February 28 |
Using this database (stored on the computer), you could:
One reason for using a database to store information is that it can be easily sorted. You can sort a database file on anything that is a field. In the example above, you could put the information in order based on any of the three fields. If you had used only one field for name, then you would not be able to sort by last name.
Sorts can be ascending (A to Z, smaller numbers first) or descending (Z to A, larger numbers first). You may also combine sorts, so that items with the same value in one field can be sorted in a particular order as well. In the example above, there are two records whose birthdate is the same. These could be sorted ay name as well.
Click here to try sorting a small database
Searching
Database files make it easy to locate information. You can search for a particular value in a particular field. In the example above, we could search for all the February birthdays or all the children whose name is Maria.
Searches can be more specific through the use of AND, OR and NOT. AND makes the search more specific, since two conditions must both be true. For example, if you are searching the ERIC database for articles that have "computers" in the SUBJECT field and "research" in the TITLE, then only articles with both will be shown.
Click here for a diagram of AND
Using OR generates more "finds" since all of one condition and all the other condition are both included. In the ERIC database examples above, all articles with "computers" in the SUBJECT field (no matter what is in the TITLE field) and all articles with "research" in the TITLE (no matter what is in the SUBJECT field) will be included in the list. The OR list would be much longer than the AND list.
Click here for a diagram of OR
NOT is used to exclude some values from the list. For example, suppose this search was specified: NOT (TITLE contains "computer"). All articles without "computer" in the title would be listed. NOT is more commonly combined with AND to produce a very specific search. For example, SUBJECT contains "technology" AND NOT (SUBJECT contains "computer") would find all the ERIC articles about technology other than computers.
Click here for a diagram of NOT
Click here to download a sample database of student test scores (in Excel format)
Click here to visit the ERIC database of educational articles through AskERIC
OR...visit the CSUDH library for some full text ERIC articles
Web search engines work the same way as the ERIC examples shown above. A search engine is really a huge database of information about websites. In most cases, the words you type in will be searched for as though you had typed "AND". Others assume they are an OR search, while many include both. Some search engines have an "advanced search" option in which the user can specify AND, OR, and NOT.
Click here to visit a search engine (YAHOO)
Merging
Information in database files can be automatically merged into other types of files. For example, form letters (and the labels used to send them) are most often generated using information from a database file. For example, a school could send a letter to all students who have been absent for more than 10 days if the database file includes the address and the absences. Click here for a simulation of merging.
