ITGS Syllabus

Friday, April 14, 2006

Topic 58

Databases: Design and creation concepts

Updating Data by Su Chen

Information is updating every moment. Lots of new things are going to put online to share with other people. People usually say updating, uploading, but the question is what do they really update. We are not updating information, news or other things, but the database. Database is a collection of varies information, may include bibliographic textual or numeric data. Thus, we can say that database is one the most important part in the computer system.
Usually there are two application pages that use to update data in a database. One is an update form, second is an update action page which most of us use in the daily life. For example, every time when you want edit something on your website (my space), often you just change what you want in the different sections. In the end you click ok, submit or other buttons that have update this function to complete your updating.

An update form is similar to an insert form, but remembers there are two key differences: 1. an update form contains a reference to the primary key of the record that is being updated. The term primary key often refers to a field or combination of fields in a database table that uniquely identifies each record in the table. For instance, in a table of employee names and addresses, only the Employee ID would be unique to each record. 2. An update form is usually populated with existing record data because the form’s purpose is to update data. In other words, it just means that we update the data that already existed there.

By knowing these, one can easily update the data at anytime and even can create their own update forms or update action pages. The important thing to create an update action page with cfupdate is that to use cfup code, you must include the field or fields that make up the primary key in your form submittal. The cfupdate tag automatically detects the primary key fields in the table that your are updating and looks for them in the submitted form fields. ColdFusion uses the primary key fields to select the recordto update. Therefore, you cannot update the primary key value itself. Then it uses the remaining form fields that are submitted to update the corresponding fields in the record. Finally your form only needs to have fields for the database fields that you want to change.

Different companies have their different update form, but the essential function of this form does not change. It allows people to update their newest data, makes things become simple and convenient. Without Updating data, you may never sure about anything of him. You may find out that mailing address is no longer accurate. Therefore, you may lose contact with him. Thus, updating data is important not only because it saves out time but also through this we can know the current situation----what’s going on in the world. Luckily, people can update the data at the same time. In other words, not only you, but others can also change this data whenever they want. The good side of this is that you can know the changing immediately. So suppose to say you update some data about Microsoft market share, however this data may only apply to the past. Thus, someone else may just update the newest data to show the recent situation. You may learn some new things from updating.

The social issue of updating data is that, if in a multi-user environment, like what I say before, since more than one person might be working with the same record at the same time. Because of this, thus other people can change or even delete the same data that you’re trying to edit. You are not the only one that has the right to edit it. So you might occasionally encounter data conflicts with others as they work. Therefore, under this circumstance, updating data will just make our lives harder. People need to spend more time on data process.


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