The concept comparison between Notes database and relational database

We know that in the database theory, there are external patterns, patterns and internal patterns. The external mode (also known as child mode or user mode) is a description of the logical structure and characteristics of the local data used by the database users, and is the data view of the database user, such as the structure, type, length and classification of the view and table. The pattern is a description of the logical structure and characteristics of all the data in the database, and it is the public data view of all the users, such as the structure, type, length, classification level of the different tables, and the logical relationship between the table and the table. Internal mode (also called physical mode) is the description of data physical structure and storage mode, which is the representation of data inside the database, such as storage, indexing, data compression, encryption and clustering. To compare the Notes document database with the relational database, let's take a look at the Notes document database concepts.

1. Notes database file (. NSF): The database file contains the data for the application, and its structure consists of forms, fields, folders, views, and other display features, such as navigators and database icons. It is divided into two parts: design elements, data documents. Design elements are forms (form), fields (field), Views, folders, and so on, which form the basis of an application. Data documents (document) are data information submitted by the user. Image, it is the user in the form of the existence of documents, such as: a document.

2. Form: In the NSF database file, a single NSF database can define multiple forms, which consist of multiple form elements. Form elements are components that are used to create the appearance and functionality of a form. As with pages, forms can contain: text, horizontal baselines, tables, sections, graphics, image maps, links, automatic features, applet, attachments, embedded elements, and HTML. A form can consist of multiple child forms, which are collections of form elements that are saved as a separate object. A child form can contain the same elements as a regular form. Using a child form can save you time from a redesign. If you change a field for a child form, every form that you use to the subform is updated. Common uses for child forms include adding company labels to business documents, or adding mailing label information to mail and note forms. A child form can be used as a permanent part of a form, or it can be conditionally displayed based on the results of a formula. For example, you can give users a choice that allows them to use different images and styles to customize mail forms for various types of mail messages, such as notes, warnings, or letters. The domain name that you use in the child form cannot be used elsewhere in the form. The changes that you make to the subform affect all forms and documents that use the child form.

3. Field: field is an important element of form, for a Notes database, the input of external data through the domain, the library to store data display also depends on the domain. The field type determines the type of information that the field can contain. The user can define the field type in the Domain Properties box. The field types are text, date/time, Number, dialog box list, check box, radio button, list box, combo box, Rich text, author, name, reader, password, and formula. The primary properties of the domain are:

Editable: Data can be generated by using a button to execute a formula (formulas) or script (scripts).

Implied: only for storage, not for display, the data for the field is not displayed when the document is displayed.

Quasi many values: A single domain allows users to deposit multiple values.

4. Document: In Lotus Notes, information is saved as a document in a database, and one document corresponds to a record in a relational database.

5. View: View is the main browsing window for Lotus Notes Chinese files, and when a selection of a view is given, the document you see through that view is a qualifying document, and each view contains a document that meets certain criteria. In addition to the selection criteria, views can be categorized and sorted by different characteristics, allowing us to quickly navigate to the document we are looking for. For simple queries, you can not write any programs, but by sorting and sorting the views in a reasonable way. is intuitive to the user, and can print out the view displayed on the screen. If the selection criteria for a view is: Select Form= "Notify", the document that we see is a notification when the view is opened.

6. Folder: Folders are also one of the browsing windows of a document, but unlike views, folders do not have selection criteria. Because Lotus Notes documents can be shared, folders can also be shared or private. The documents inside are placed through putinfolder and must be removed by Removefromfolder.

It is easy to see that in the Notes document database, the schema is also the table definition form (form) and field (field), which is used to display and save data to the user. An out mode is usually a view or folder that a user can see.

From a certain point of view, form, which provides a way for users to browse through the document information stored in the NSF file, form is also a mechanism of internal patterns, and we can implement different forms for different users so that different users can see the Document information (form) differently. On the other hand, because in notes, the form itself is not stored in the document, it only works when the document is displayed, and the form is a manifestation of the external schema of the database. Unlike relational databases, a row of data in a table must conform to the table definition. A document in the Notes document database can not conform to any format definition or data constraint, and data constraints are valid only when the user enters data through the form.

We can assume that a view or folder in Notes is an external pattern that provides a way for users to browse and find document data, and we can customize different views or folders for different users.