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INTERACT.HLP
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1993-01-04
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*********************************************************************
Interactive CodeBase for DOS
(CID)
Help File
*********************************************************************
This demo program gives you the opportunity to try out most of the
CodeBase 5.0 functions interactively. Many of the functions will
be familiar to you if you do some xBASE programming.
This demo is designed to let you call the CodeBase 5.0 functions exactly
as if you had written a C program. As such you may do any combination
of function calls and watch the return codes appear. With any open ended
program of this sort, it is best to do a couple of structured examples
before experimenting.
Listed below are a couple of sequences that you can use to get started
using Interactive CodeBase 5.0 for DOS.
You may wish to read this information, and then print it out before
actually running CID. This information is stored in INTERACT.HLP.
CREATING A DATABASE
===================
C4CODE | safety = FALSE. This flag determines whether to over write an
existing file with a new one. It is generally
a good idea to set this to FALSE when creating
a database.
D4DATA | d4create()
This function actually creates the data base and
index files. When selected, d4create() prompts
you for the directory and name of the database
to create. You may enter in any directory (or
press <ENTER> for the default current directory)
and choose any name and extension for the
database.
Use DEMO2.DBF as the database name, and create
the following fields:
NAME TYPE LEN DEC
=======================
NAME C 20 0
AGE N 3 0
BIRTH D 8 0
GPA N 3 1
NAME This is the name of the field. This field name
should be unique for this data file. The same
name can occur in different databases.
TYPE xBASE supports five different types of fields:
They are:
C Character
D Date
L Logical (TRUE or FALSE)
M Memo
N Numeric
LEN This determines the number of spaces to reserve
for the new field (including decimal places, if
applicable). Date fields have a length of 8.
Memo fields are defined with a length of 10.
Logical fields have a length of 1.
DEC If the field is a numeric that is to have decimal
places, you must specify them in this entry area.
If you are not using a numeric field, this should
be set to 0.
The logical order of the database can be modified
by using indexes. Each order is stored as a
'tag'. Tags can be specified when the database
is created using the d4create(), or afterwards
using the i4create().
Create the index using the d4create() and specify
the following items:
NAME KEY EXPR FILTER UNIQUE DESCENDING
=================================================
NAMETAG NAME .NOT.DELETED() 0 0
AGETAG AGE 0 1
NAME The name here is the title with which you
reference the particular sort order. Each tag
for a database must have a unique name.
KEY EXPR This is what the tag is sorted by. This may be
any field or combination of fields. Most dBASE
expressions work in the key expression. Examples
could be:
LAST_NAME+FIRST_NAME or SUBSTR(NAME,1,3) or
NAME+STR(AGE,3,0)
FILTER If only a portion of the database are to be in the
index, specify a filter using most logical
dBASE expressions. Some examples are:
AGE > 18 or NAME > "A".AND.SUBSTR(NAME,1,3)<>"SMI"
or MONTH(BIRTH) = 12
UNIQUE If duplicate records are allowed in the index, set
the unique flag to 0 (FALSE).
DESCENDING Indexes are generally ordered from A...Z 0...9,
however, if the DESCENDING flag is set, the order
is reversed 9...0, Z...A and so on. This is useful
for dates.
ADDING NEW RECORDS
==================
D4DATA | d4append_blank()
This function creates a new record and appends it
to the bottom of the database. The fields are
filled with spaces (hence the _blank in the
function call).
F4FIELD | f4assign()
This function puts data into a field. You must
specify the database, the field, and the
information you wish to store. Since xBASE
stores all data in a character form, you may use
this function for all data types.
Using date fields, however, you must enter the
date in the CCYYMMDD format. (eg.19910101 is
January 1, 1991).
f4assign() overwrites any existing data in the
field. If you wish to create multiple records,
use d4append_blank() before each set of data is
modified.
Add three records using the following information:
NAME AGE BIRTH GPA
=============================
PETER 20 19720202 3.8
ANDREW 15 19770404 4.0
JAMES 30 19620101 2.1
CLOSING THE DATABASE
====================
D4DATA | d4close() You may close a database by executing this
function. If more than one database is open, you
can close them all using d4close_all(). CID
automatically closes all the databases when QUIT
is executed.
OPENING AN EXISTING DATABASE
============================
C4CODE | auto_open = FALSE
Set this flag if you do not wish to open an
existing index file automatically with the d4open().
D4DATA | d4open()
d4open() opens a database that already has been
created. The database need not have been created
using CID, but may be also created using dBASE IV,
FoxPro, Clipper, or dBASE III. If the
C4CODE:auto_open flag is TRUE, d4open()
automatically opens any associated production index
file.
Production index files are created using d4create()
or by creating an index file with dBASE IV or
FoxPro.
I4INDEX | i4open() i4open() opens an index file associated with
a database.
D4DATA | d4tag_select() Since an index file can contain several orderings
it is necessary to specify which ordering to
use for functions that use the logical ordering,
such as d4skip(), d4top(), d4bottom() and d4seek().
d4tag_select() is used for just this purpose.
Open the DEMO2.DBF file and the DEMO2 index file.
USING THE BROWSER
==================
Once a database has been opened or created, you can
browse the data by selecting the BROWSER option of
the main menu. Listed below are some of the things
you can do using the browser:
Modify a field Press <ENTER> while the field is highlighted, type
in your new information and press <ENTER>. The
browser automatically calls f4assign() for you.
Select a tag Press <ESC> to return to the top level menu and
ordering choose d4tag_select. Selecting BROWSE again causes
the browse window to be re-drawn with the ordering.
Insert a new Press the Insert key and a new record is added.
record The browser automatically calls d4append_blank()
for you.
Mark a record Press the Delete key and the current record is
for deletion marked for deletion. Deleted records have the
leftmost field area filled in with an asterisk (*).