FATS - Fast Access Tree System Table of Contents Programming Interfaces Visual Basic for DOS

The following VB DOS example demonstrates the use of the FATS  indexing commands:

	"C" Create Indexfile (Creates a index file with the specified characteristics.)
	"O" Open Indexfile (Makes a index file available for access.)
	"K" Close Indexfile (Releases a index file from availability.)
	"I" Insert Record (Insert a new record.)
	"F" Search First (Gets the key value and record number of the data record with the first key value.)
	"L" Search Last (Gets the key value and record number of the data record with the last key value.)
	"N" Search Next (Gets the key value and record number of the data record following the current record.)
	"A" Search Next After (Gets the key value and record number of the data record whose key value is greater than the requested key value.)
	"E" Search Previous Before (Gets the key value and record number of the data record whose key value is less than the requested key value.)
	"Y" Auto Refresh (Specifies file locking and cache modes in single- and multi-user environments.)

REM   FATS 02.30
REM   (c) GCS Software, Udo Gertz 1993-1998
REM
REM   Test program (Visual Basic for DOS)
REM 
REM   Build the test data file customer.dat.
REM
REM   19-03-2009 U.Gertz


PRINT "This Test Program was designed for Visual Basic (MS-DOS)"
PRINT
PRINT "To compile and link the test program, use ONE of the following methods:"
PRINT
PRINT "  1. METHOD: Linking FATS to the program"
PRINT
PRINT "     BC TST1_ENG"
PRINT "     LINK TST1_ENG FATS.OBJ FATS_VBD.OBJ"
PRINT
PRINT "  2. METHOD: Calling the Workstation Engine"
PRINT
PRINT "     BC TST1_ENG"
PRINT "     LINK TST1_ENG FATSVBDR.LIB   (FATS Standard Version FATS_WE.EXE)"
PRINT
PRINT "     or if you own the extended version of FATS:"
PRINT
PRINT "     LINK TST1_ENG FATSXVBR.LIB   (FATS Extended Version FATSXWE.EXE)"
PRINT
INPUT "Please press the [ENTER] key ...", X$
PRINT


REM  -------> Activation of Network Operation
REM
REM  FATS is standardly equiped for the network environment.
REM  Nearly all commands can be executed both in single workstation
REM  and network environment. With the  "Y" Auto Refresh command you
REM  determine the behavior of FATS accessing all index files.
REM  Normally it is sufficient to apply this instruction one time at
REM  the program start whereby the specified access mode will apply
REM  to all coming opened files, i.e. they are accessed either with
REM  network (Y\2) or single workstation access (Y\0).

REM CALL FATSBASIC( "Y\2", ERRORCODE%, RECNO&, KEYLEN% )

REM  -------> Open file with test data

OPEN "R", #1, "..\..\..\DEMODATA\CUSTOMER.ASC", 105
FIELD #1, 5 AS F1$, 25 AS F2$, 25 AS F3$, 25 AS F4$, 5 AS F5$, 20 AS F6$

REM  -------> create data file

PRINT "Creating Data File ..."

OPEN "R", #2, "CUSTOMER.DAT", 128
FIELD #2, 1 AS DELETEDMARK$,_
          5 AS CUSTID$,_
         25 AS NAME$,_
         25 AS JOB$,_
         25 AS STREET$,_
          5 AS ZIP$,_
         20 AS CITY$

REM  -------> Create index file


REM   "C" Create Indexfile
REM
REM  With this command you create an index file, whereby a possibly
REM  already existing file with the same name is deleted.
REM  After the file is created it will be opened with the opening
REM  flags defined with the command  Auto Refresh (Y) and can be
REM  accessed under the file number you specified.
REM
REM  Max. 200 primary keys per data record can be administered in an
REM  index file, the max. key length amounts to 240 characters.
REM
REM  Full path names must be specified using forward slashes (/)
REM  instead of Backslashes (\), because FATS normally uses the
REM  Backslash character as delimiter.
REM  You may change the delimiters by placing the desired character
REM  as the first character of the command string,
REM  e.g. szCmnd = "&C&C:\ARTICLES.KEY&1&1&A&1". Any character with
REM  an Ascii code less then 48 will be accepted.
REM
REM  The syntax of the command string:
REM
REM    szCmnd = "C\{Filename}\{KeyLength}\{KeyCount}\{KeyType}\{FileNo}"
REM
REM      FileName   filename, perhaps with an additional path
REM                 (e.g. C:/DATA/ARTICLES.KEY or ARTICLES.KEY)
REM
REM      KeyLength  Maximum key length (1-250)
REM                 If you choose to have more than one key for
REM                 this index file, you may specify the length
REM                 for each key (separated by a semicolon ";")
REM                 to conserve diskette space.
REM                 Otherwise, the maximum length applies to all
REM                 keys, i.e. every key will occupy the maximum
REM                 space.
REM
REM      KeyCount   Number of primary keys (1-200)
REM
REM      KeyType    Key type (A = Ascii text, I = Integer)
REM
REM      FileNo     File number (1-40)


PRINT "Creating Index File ..."

CALL FATSBASIC( "C\CUSTOMER.KEY\5;25\4\A\1", ERRORCODE%, RECNO&, KEYLEN% )
IF ERRORCODE% <> 0 GOTO ENDE


REM  ========================================================================
REM            Insert Records
REM  ========================================================================

PRINT
PRINT "290 records will be inserted into the data file."
PRINT "For each record 4 keys will be stored in the index file."
INPUT "Please press the [ENTER] key ...", X$

FOR X=1 TO 290

  GET #1, X
  LSET DELETEDMARK$ = " "
  LSET CUSTID$ = F1$
  LSET NAME$ = F2$
  LSET JOB$ = F3$
  LSET STREET$ = F4$
  LSET ZIP$ = F5$
  LSET CITY$ = F6$

    REM   "I" Insert Record
    REM
    REM  This command is used to insert the primary keys of a new
    REM  data record into the index file. After the insert, the
    REM  record number of the new record is returned in the "RECNO"
    REM  variable. You can use this record number to write the data
    REM  record to the data file.
    REM
    REM  The number of keys included in the command string must equal
    REM  the number of primary keys you specified in the
    REM  Create Indexfile (C) command.
    REM
    REM  The length of the transferred keys may not exceed the maximum
    REM  key length specified with the Create Indexfile (C) command.
    REM  Variable length keys will be padded with the Ascii char 0 to
    REM  the maximum key length.
    REM
    REM  The syntax of the command string:
    REM
    REM    szCmnd = "I\{FileNo}\{KeyStr1}[\{KeyStr2}[\{KeyStr3}]]"
    REM
    REM      FileNo     File number
    REM
    REM      KeyStr#    Key value

    CMND$ = "I\1\"
    CMND$ = CMND$ + RTRIM$(CUSTID$) + "\" + RTRIM$(NAME$) + "\" + RTRIM$(JOB$) + "\" + RTRIM$(ZIP$ + CITY$)

  CALL FATSBASIC( CMND$, ERRORCODE%, RECNO&, KEYLEN% )
  IF ERRORCODE% <> 0 GOTO ENDE

  PRINT NAME$; " --> RecNo "; RECNO&
  PUT #2, RECNO&

NEXT X

CLOSE #1

REM   "K" Close Indexfile
REM
REM  This command closes the index file with the specified
REM  file number.
REM
REM  If you have activated the cache algorithm with the command
REM  Auto Refresh (Y), the possibly still in the cache buffers
REM  presented data are automatically written on the disk.
REM
REM  If the cache is inactive after every FATS command all
REM  changed data are written on the disk. Therefore closing of
REM  a file is necessary only before terminating the application.
REM
REM  If you omit the parameter "FileNo", then all opened index
REM  files are closed. This version is recommended before the
REM  termination of the application program.
REM
REM  The syntax of the command string:
REM
REM    szCmnd = "K\{FileNo}"
REM
REM      FileNo     File number

CALL FATSBASIC( "K\1", ERRORCODE%, RECNO&, KEYLEN% )


REM  ========================================================================
REM            Search
REM  ========================================================================


REM   "O" Open Indexfile
REM
REM  With this command you open an existing index file with
REM  the opening flags defined with the command Auto Refresh (Y).
REM  After the file was opened it can be accessed under the
REM  file number you specified. An index file already opened
REM  with the same file number is closed before this command
REM  is executed.
REM
REM  Full path names must be specified using forward slashes (/)
REM  instead of Backslashes (\), because FATS normally uses the
REM  Backslash character as delimiter.
REM  You may change the delimiters by placing the desired character
REM  as the first character of the command string, e.g.
REM  szCmnd = "&O&C:\ARTICLES.KEY&1". Any character with an Ascii
REM  code less then 48 will be accepted.
REM
REM  The syntax of the command string:
REM
REM    szCmnd = "O\{FileName}\{FileNo}"
REM
REM      Filename   filename, perhaps with an additional path
REM                 (e.g. C:/DATEN/ARTICLES.KEY or ARTICLES.KEY)
REM
REM      FileNo     File number

CALL FATSBASIC( "O\CUSTOMER.KEY\1", ERRORCODE%, RECNO&, KEYLEN% )


REM  -------> Print all customers, sorted in ascending order by NAME

PRINT
PRINT "This list shows some fields from the Customer Table,"
PRINT "sorted in ascending alphabetical order on the Customers"
PRINT "surname and forename."
PRINT
INPUT "Please press the [ENTER] key ...", X$


REM   "F" Search First
REM
REM  This command enables your application to retrieve the
REM  record number corresponding to the first key value for
REM  the specified key number.
REM
REM  The syntax of the command string:
REM
REM    szCmnd = "F\{KeyNo}\{FileNo}"
REM
REM      KeyNo      Key number
REM
REM      FileNo     File number

CMND$ = "F\2\1"

LOOP1:

  CALL FATSBASIC( CMND$, ERRORCODE%, RECNO&, KEYLEN% )
  IF ERRORCODE% <> 0 GOTO LABEL1

  FATSKEY$ = SPACE$( KEYLEN% )
  CALL FATSGETKEY( FATSKEY$ )

  GET #2, RECNO&
  PRINT NAME$; " "; JOB$; " --> RecNo "; RECNO&

  REM   "A" Search Next After
  REM
  REM  With this command your application can retrieve the record
  REM  number corresponding to the first key value which is greater
  REM  than the key value you specify.
  REM  If a duplicate key exists, the next higher record number of
  REM  the next duplicate will be returned. The key value you specify
  REM  with "KeyString" don't have to be a valid key in the index file.
  REM
  REM  Unlike the "Search Next" command, this command can be used in
  REM  a network environment.
  REM
  REM  The syntax of the command string:
  REM
  REM    szCmnd = "A\{KeyNo}\{RecNo}\{FileNo}\{KeyString}"
  REM
  REM      KeyNo      Key number
  REM
  REM      RecNo      Record number
  REM
  REM      FileNo     File number
  REM
  REM      KeyString  Key value

  CMND$ = "A\2\" + STR$( RECNO& ) + "\1\" + FATSKEY$
  GOTO LOOP1

LABEL1:


REM  --------> print all customers, sorted in ascending order by JOB

PRINT
PRINT "Two columns - JOB and NAME are displayed, sorted in ascending"
PRINT "order by the JOB field."
PRINT
INPUT "Please press the [ENTER] key ...", X$

CMND$ = "F\3\1"

LOOP2:

  CALL FATSBASIC( CMND$, ERRORCODE%, RECNO&, KEYLEN% )
  IF ERRORCODE% <> 0 GOTO LABEL2

  GET #2,RECNO&
  PRINT JOB$; " "; NAME$; " --> RecNo "; RECNO&

  REM   "N" Search Next
  REM
  REM  With this command your application can retrieve
  REM  the record number corresponding to the first key
  REM  value which is greater than the key value recently
  REM  returned by one of the search commands, which have
  REM  to be executed as the latest command.
  REM  If a duplicate key exists, the next higher record
  REM  number of the next duplicate will be returned.
  REM
  REM  Each modification of the index file by inserting or
  REM  deletion of keys makes an internal pointer invalid
  REM  that is necessary for this instruction. You better
  REM  use the command  Search Next After (A) because this
  REM  can happen in the network environment from any station.
  REM
  REM  If there is no key in sequence FATS will return an
  REM  errorcode of 15.
  REM
  REM  The syntax of the command string:
  REM
  REM    szCmnd = "N\{FileNo}"
  REM
  REM      FileNo     File number

  CMND$ = "N\1"
  GOTO LOOP2

LABEL2:


REM  --------> print list with records sorted by ZIP and CITY

PRINT
PRINT "Three columns - ZIP, CITY and NAME are displayed, sorted in"
PRINT "descending order by ZIP then CITY."
PRINT
INPUT "Please press the [ENTER] key ...", X$


REM   "L" Search Last
REM
REM  This command enables your application to retrieve the
REM  record number corresponding to the last key value for
REM  the specified key number. If duplicates exist for the
REM  last key value, the record number returned identifies
REM  the last duplicate, that is, the one inserted most
REM  recently.
REM
REM  The syntax of the command string:
REM
REM    szCmnd = "L\{KeyNo}\{FileNo}"
REM
REM      KeyNo      Key number
REM
REM      FileNo     File number

CMND$ = "L\4\1"

LOOP3:

  CALL FATSBASIC( CMND$, ERRORCODE%, RECNO&, KEYLEN% )
  IF ERRORCODE% <> 0 GOTO LABEL3

  FATSKEY$ = SPACE$( KEYLEN% )
  CALL FATSGETKEY( FATSKEY$ )

  GET #2, RECNO&
  PRINT ZIP$; " "; CITY$; " "; NAME$; " --> RecNo "; RECNO&

  REM   "E" Search Previous Before
  REM
  REM  With this command your application can retrieve the record
  REM  number corresponding to the first key value which is less
  REM  than the key value you specify.
  REM  If a duplicate key exists, the next lower record number of
  REM  the previous duplicate will be returned. The key value you
  REM  specify with "KeyString" don't have to be a valid key in the
  REM  index file.
  REM
  REM  Unlike the "Search Prev" command, this command can be used in
  REM  a network environment.
  REM
  REM  The syntax of the command string:
  REM
  REM    szCmnd = "E\{KeyNo}\{RecNo}\{FileNo}\{KeyString}"
  REM
  REM      KeyNo      Key number
  REM
  REM      RecNo      Record number
  REM
  REM      FileNo     File number
  REM
  REM      KeyString  Key value

  CMND$ = "E\4\" + STR$( RECNO& ) + "\1\" + FATSKEY$
  GOTO LOOP3

LABEL3:

ENDE:

REM  --------> Close index file

CALL FATSBASIC( "K\1", ERRORCODE%, RECNO&, KEYLEN% )

CLOSE #2

END

© 2008  GCS Software, Udo Gertz