>Hi ,
> I have two problems now.
>
> Firstly ,I doubt if there is any command that can add/remove field in table during runtime ?
>

Look at the ALTER TABLE command.

> Then ,I try to use subtran to remove chr(13) in memo field ,but fail.
>Code is here :
> StrA = chr(13)
> StrB = Chr(13) + Chr(13)
> StrC = Subtran(StrC ,StrA ,StrB)
>

To remove all CHR(13) occurances from a memory field:

StrC = CHRTRAN(StrC, CHR(13), "") && faster, but limited see docs

or

StrC = STRTRAN(StrC, CHR(13), "") && not subtran!!!!

To reduce all occurances of multiple CHR(13) to a single CHR(13)

StrC = STRTRAN(StrC, CHR(13) + CHR(13), CHR(13)) && cannot use CHRTRAN here