- See an attribute as a feature
- What is an attribute?
- Attributes describe entities
- Is the attribute a field?
- Attribute definition
See an attribute as a feature
The database is more powerful than the spreadsheet it seems because it has a huge search capability. Relational databases refer to records in different tables and perform complex calculations on large amounts of related data. The information is organized in such a way that it is easy to manage, consult and update.
What is an attribute?
The database is made up of tables. Each table has columns and rows. Each row (called a tuple) is a set of data applied to a single element. Each column (attribute) contains a description of the characteristics of the rows. A database attribute is the name of a column and the contents of the fields below it in a table in the database.
If you sell products and enter them into a table with columns for ProductName, Price, and ProductID, each of those headings is an attribute. In each field below these headings, enter product names, prices, and product IDs, respectively. Each of the field items is also an attribute.
An attribute is a single piece of data in the tuple to which it belongs. Each tuple is a set of data applied to a single element.
This makes sense when you think about it, since the non-technical definition of an attribute is that it defines a characteristic or quality of something.
Attributes describe entities
Think of a database developed by a company. Most likely it will contain tables – also referred to as entities by database designers – for customers, employees, and products. The Products table defines the characteristics of each product. They can contain product ID, product name, supplier ID (used as a foreign key), quantity, and price. Each of these attributes is an attribute of a table (or entity) called Products.
Consider this excerpt from the oft-cited Northwinds database:
The column names are product attributes. The entries in the column fields are also product attributes.
Is the attribute a field?
Sometimes the conditions are field and attributes are used interchangeably and for most purposes they are the same. However, a field describes a particular cell in a table found in a row, while an attribute describes a characteristic of an object in a constructive sense.
In the table above ProductName in the second row − Chang † This field. If you are talking about products in general, ProductName is the product column. This is an attribute.
Attributes are defined in terms of their domain. The domain defines the allowed values that an attribute can contain. This includes the data type, length, values, and other details.
For example, the domain for an attribute ProductID can indicate a numeric data type. The attribute can be further defined to require a specific length, or to indicate whether a null or unknown value is allowed.