SUMMARY
If you want to create an index on part of a character field, you can create
the index with the SUBSTR() function. The following code is used for
indexing on the first five characters of a field called NAME:
INDEX on SUBSTR(Name,1,5) TAG partnam
If the NAME field contains a last name and first name separated by a comma,
indexing on the last name can be performed as follows:
INDEX on SUBSTR(Name,1,(AT(",",Name,1)-1)) TAG lastname
However, if the above command is used, FoxPro will create an index tag that
does not order the database accordingly. For example, with the NAME field
in a five-record database as listed below
Record 1: Brown, John
Record 2: Williams, Mary
Record 3: William, Bob
Record 4: Willis, James
Record 5: Williams, Mark
Record 6: William, Bill
using the INDEX statement above will result in the database being ordered
as follows:
Record 1: Brown, John
Record 2: Williams, Mary
Record 3: William, Bob
Record 5: Williams, Mark
Record 6: William, Bill
Record 4: Willis, James
To have the database ordered accordingly, you must use the PADR() function
to pad the string returned by the SUBSTR() function with spaces equal to
the length of the field. For example:
INDEX on PADR(SUBSTR(Name,1,(AT(",",Name,1)-1)),15," ") TAG partnam
For more information, see the "Commands & Functions" manual for FoxPro
version 2.0 or the "Language Reference" manual for FoxPro version 2.5.