CREATEINDEX Statement
 ----------------------------------------------------------------------------


 Action

 Creates an index consisting of one or more columns of an ISAM table.


 Syntax

  CREATEINDEX -#-filenumber%, indexname$, unique%, columnname$-,
 columnname$-...


 Remarks

 The  CREATEINDEX statement uses the following arguments.

-----------------------------------------------------------------------------
 Argument                                Description
 ----------------------------------------------------------------------------
  filenumber%                            The number used in the  OPEN
                                         statement to open the table.

  indexname$                             The  indexname$ is the name of the
                                         index until the index is
 Argument                                Description
 ----------------------------------------------------------------------------
                                         index until the index is
                                         explicitly deleted. It follows the
                                         ISAM naming conventions (details
                                         are provided later in this entry).

  unique%                                A non-zero value for  unique%
                                         indicates the index is
                                         unique--no two indexed values
                                         can be the same. A value of zero
                                         for  unique% means the indexed
                                         values need not be unique.

  columnname$                            Names the column or columns to be
                                         indexed. The name follows the ISAM
                                         naming conventions. If more than
                                         one column name is given,
                                         CREATEINDEX defines an index based
                                         on the combination of their values.
                                         The argument  columnname$ must
 Argument                                Description
 ----------------------------------------------------------------------------
                                         The argument  columnname$ must
                                         appear in the  TYPE statement used
                                         when the table was created.



 When you initially open a table, the current index is the null index. The
 null index  represents the order in which records were added to the file.
 Once an index has been created, it can be used any number of times until it
 is deleted from the database.

 Use  SETINDEX to make an index the current index and impose its order on the
 presentation of records in a table.


 Note

 Columns that are arrays, user-defined types, or strings longer than 255
 characters cannot be indexed.


 ISAM names use the following conventions.

   -   They have no more than 30 characters.

   -   They use only alphanumeric characters (A-Z, a-z, 0-9).

   -   They begin with an alphabetic character.

   -   They include no BASIC special characters.


 See Also

  DELETEINDEX,  GETINDEX$,  SETINDEX


 Example

 This example uses the  CREATEINDEX,  SETINDEX and  DELETEINDEX statements to
 index an ISAM file in several ways. It displays records from the file using
 the  GETINDEX$ and  BOF functions and the  MOVEFIRST,  MOVELAST,  MOVENEXT,
 and  MOVEPREVIOUS statements.

 The program uses a file called BOOKS.MDB, the sample ISAM file that SETUP
 copies to your disk.

 DEFINT A-Z
 TYPE BookRec
     IDNum AS DOUBLE             ' Unique ID number for each book.
     Title AS STRING * 50        ' Book's title.
     Publisher AS STRING * 50    ' Book's publisher.
     Author AS STRING * 36       ' Book's author.
     Price AS CURRENCY           ' Book's price.
 END TYPE

 DIM Library AS BookRec          ' Record structure variable.
 DIM msgtxt AS STRING

 CONST Database = "BOOKS.MDB"    ' Name of the disk file.
 CONST TableName = "BooksStock"  ' Name of the table.
 tablenum = FREEFILE             ' File number.

 OPEN Database FOR ISAM BookRec TableName AS tablenum
 CREATEINDEX tablenum, "A", 0, "Author"
 CREATEINDEX tablenum, "I", 1, "IDnum"
 CREATEINDEX tablenum, "T", 0, "Title"
 CREATEINDEX tablenum, "C", 0, "Price"

 ' Display static instructions.
 CLS . LOCATE 13, 30
 PRINT "Choose a key."
 PRINT SPC(9); "Move to."; TAB(49); "Order by. X"
 PRINT . PRINT SPC(9); "F - First record"; TAB(49); "A - Author"
 PRINT . PRINT SPC(9); "L - Last record"; TAB(49); "I - ID Number"
 PRINT . PRINT SPC(9); "N - Next record"; TAB(49); "T - Title"
 PRINT . PRINT SPC(9); "P - Previous record"; TAB(49); "C - Cost"
 PRINT . PRINT SPC(9); "Q - Quit"; TAB(49); "X - No order"
 LOCATE 3, 1. PRINT TAB(37); "Books"
 PRINT STRING$(80, "-");
 VIEW PRINT 5 TO 10          ' Set viewport for displaying records.age.
 MOVEFIRST tablenum
 DO
     ' Display current record.
     CLS
     RETRIEVE tablenum, Library
     PRINT "Author.    "; Library.Author;
     PRINT TAB(49); "ID #"; Library.IDNum
     PRINT "Title.     "; Library.Title
     PRINT "Publisher. "; Library.Publisher
     PRINT "Cost.     "; Library.Price
     PRINT SPC(30); msgtxt
     PRINT STRING$(64, "-");
     IF GETINDEX$(tablenum) = "" THEN
         PRINT STRING$(15, "-");
     ELSE
         PRINT "Index in use. "; GETINDEX$(tablenum);
     END IF

     ' Get keystroke from user.
     validkeys$ = "FLNPQATICX"
     DO
         Keychoice$ = UCASE$(INKEY$)
     LOOP WHILE INSTR(validkeys$, Keychoice$) = 0 OR Keychoice$ = ""
     msgtxt = ""

     ' Move to appropriate record, or change indexes.
     SELECT CASE Keychoice$
     CASE "F"
         MOVEFIRST tablenum
     CASE "L"
         MOVELAST tablenum
     CASE "N"
         MOVENEXT tablenum
         IF EOF(tablenum) THEN
             MOVELAST tablenum
             BEEP. msgtxt = "** At last record **"
         END IF
     CASE "P"
         MOVEPREVIOUS tablenum
         IF BOF(tablenum) THEN
             MOVEFIRST tablenum
             BEEP. msgtxt = "** At first record **"
         END IF
     CASE "Q"
         EXIT DO
     CASE ELSE           'User chose an index.
         VIEW PRINT
         LOCATE 13, 59. PRINT Keychoice$;
         VIEW PRINT 5 TO 10
         IF Keychoice$ = "X" THEN Keychoice$ = ""
         SETINDEX tablenum, Keychoice$
         MOVEFIRST tablenum
     END SELECT
 LOOP

 ' User wants to quit, so reset viewport, delete indexes and close files.
 VIEW PRINT
 DELETEINDEX tablenum, "A"
 DELETEINDEX tablenum, "I"
 DELETEINDEX tablenum, "T"
 DELETEINDEX tablenum, "C"
 CLOSE
 END