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Semi-Structured Data
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The main purpose of these two new objects is to facilitate the movement of data access techniques towards the new arena of semi-structured data. Up to now, we've been considering databases, which have a rigid structure of tables, rows, and fields. Data held within spreadsheets, mail servers (and so on) doesn't conform to the same rules. For example, consider the folders on a mail client that store's copies of each feedback message received in a folder system – the messages are categorized by subject area, and then by book title, and finally by chapter. The mail folder structure that reflects this categorization looks something like this:
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In fact, this system of mail folders resembles nothing so much as the file and folder system you might see if you started Windows Explorer and browsed your own hard drive. The point is that the data contained in here certainly wouldn't fit neatly into a database – yet the data storage system still has a well-defined structure.
In this example, we replace the notion of a table row that represents a single record with a new idea, whereby each node in this folder structure is considered to represent a record. Thus, each folder (such as the ASP folder in the diagram above) is a record in its own right.
As you can see, the ASP folder contains several subfolders or subnodes – we can refer to these as children. As each node can have several children, these children will be grouped together into a recordset.
This is a potential source of confusion, so let's clear it up now:
- Every single node is a single record, and can be represented by a Record object.
- When we have a collection of subfolders, then they form a recordset – although each folder might not be the same as others, it will share common information such as name and date created. The common properties form the names of the fields in the recordset.
What we're saying is that the ASP folder is a record in its own right, but it is also a field name in the Web recordset. Let's now take a closer look at the ADO object used to represent these records and fields, namely the Record object.
| << 14.3.0- Manipulating Data in your non-database Data Store | Chapter14 | 14.3.2- The Record Object >> |
