Visual FoxPro Objects


Overview

Visual FoxPro is a relational database management system developed by Microsoft. The current version is version 9.0, and Microsoft has clearly stated that this is to be the final release. Official support for Visual FoxPro 9.0 will cease from 2015. If you want to continue using and extending FoxPro beyond this point you will want to download VFPX (SEDNA) from codeplex.

Visual FoxPro supports the following file types: Project, Database, Table, Query, Connection, View, Remote View, Form, Report, Label, Program, Class, Text File, and Menu. Let’s take a look at each one of these file types in turn.

Project

A project file consists to two files. One file is the project file with the .pjx extenstion, and the other is the associated memo file with the .pjt extension. There are two ways to view the information that is contained within a project. The easiest way is to use the project manager, and the second is to use the command window. To use the command window to view the tables contents of the database file, type the following commands:

USE .PJX EXCLUSIVE NOUPDATE
BROWSE LAST

A project file is used to store a list of objects used by the project. The complete list of objects that can be stored in a project file consists of the header, screen tables, screen programs, programs, menus, queries, report forms, labels, libraries, formats, tables, indexes, files, and applications.

Project files can be used to organise files in a manner that makes them easy to work with. Using project files enables you to compile all the project files into a standalone application that can be deployed without the need to create an installation file.

Database

A database file is a container for database tables and their relationships. Within a database you can create a database schema to define tables and relationships between those tables.

Table

A table is a file that is used to hold data. You can create a table by using the table wizard or the table designer.

Data Type Default Width Default Decimal Places Change Defaults? Used To Store
Character 8 N/A Yes From 1 to 254 characters
Currency 8 N/A No Monetary amounts
Numeric 8 0 Yes Numbers used in calculations
Float 8 0 Yes Numbers used in calculations
Date 8 N/A No Dates
DateTime 14 N/A No Dates and times
Double 8 0 Yes Numeric values where extremely accurate calculation is needed
Double 8 0 Yes Numeric values where extremely accurate calculation is needed
Logical 1 N/A No .T.(true) or .F. (false)
Memo 10 N/A No Text of any length
General 10 N/A No OLE objects
Character (binary) 8 N/A Yes Text or binary up to 254 characters
Memo (binary) 10 N/A No Text or binary data of any length

Query

A query is a file that allows you to extract information from one or tables.

Connection

You can only create a connection when using a Visual FoxPro database. A connection file allows you to save database connection information. The database can be a local or remote database.

View

You can only create a view when using a Visual FoxPro database. A view file lets you create updatable queries on local tables. You cannot define triggers for a view.

Remote View

You can only create a remote view when using a Visual FoxPro database. A remote view file lets you create updatable queries on remote queries.

Form

A form is a data-entry screen that makes it easy to view, add, edit, and delete information in a database.

Report

A report file contains the design for a printed report.

Label

A label file contains the specification for mailing labels.

Program

An executable program that performs operations on FoxPro databases and tables

Class

A class file is an object-oriented programming file used to store class information. A class is a template or blueprint used to create objects. An object is an instance of a class.

Text File

A text file is a plain text file.

Menu

A menu file contains the menu specification for the menu system within a custom application.

Application

An application is a compiled Visual FoxPro application. An application with the .app extension can be run in a Visual FoxPro environment, a .exe file can run independently of the Visual FoxPro environment, and a .dll file can be called from anywhere in a Microsoft Windows environment.

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