VFP Tutorial - Data Tables
Table files
Unlike Access or SQL Server, FoxPro stores all the tables of its
database as separate files. Fields of fixed-length data are held in
a file with an extension of .dbf (database file); the
variable-length data, graphics and OLE objects have an extension of
.fpt (foxpro text and the indexes are
.cdx (compound index.
This separation has good and bad points but is proved reliable over
many years.
Designing a table
We will skip the first and most important phase of this process and assume
that the structure of the table has already been considered. This project
has a single table named CD with the following structure:
Field |
Type |
Size |
Description |
CDID |
I |
|
Unique sequential number to identify each CD |
Publisher |
C |
30 |
Publisher of this CD - eg 'Microsoft' |
CDName |
C |
30 |
Name of this CD - eg 'Visual FoxPro 8' |
SerialNo |
C |
40 |
Manufacturer's serial number |
Key |
C |
40 |
Security Key |
CDDate |
D |
|
Date received |
Creating a table
Click on the tab of the Project
Manager then right-click on
This simple application will only have a single table and does not
need the overhead of a database.
Select then
from the dialog that
appears. This dialog allows you to start the Table Wizard which can be
useful if your application matches one of the templates provided.
An explorer dialog will appear
offering to create a table named 'Table1.dbf'. Change the name to 'CD.dbf'
and save it in the same folder as the project manager file. A real life
project typically has its files in a directory tree structure but we'll
put all the files in the same folder here for simplicity.
The Table Designer will appear. Add the six fields from the list above and
click
when you have finished. Note that no size
was requested for the Integer and Date fields, the size of these data types is
fixed by FoxPro.
The greyed-out fields on the right of the designer are only available for
tables which are part of a database. You can leave the main route through
the tutorial and go to this page to learn about
Visual FoxPro databases.
Viewing the table
When you have closed the Table Designer you should see an entry like this
in the status bar at the base of the screen:
This shows that the table named 'CD' is open, it's open for your exclusive
use, it holds three records and the record pointer is on the first record.
Type:
Browse
in the Command Window to view the table.
Do not worry if the status bar is empty. If there is no table open when
you type the command then Fox will display a directory tree and ask you to
select a table.
Adding some records
Unlike Access, you cannot just create a new record by typing on a blank
line in the grid. You have to select
from the menu. This menu pad
appears whenever a Browse window is open on the desktop.
Do this three or four times and add some data to the table so that you
will have something to work with when you design a form.
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