Did you check the error? Is the logged in user an administrator? Use mydatabase may be a problem if the login string already assigns a database.
>I have tried:
>
>

>mcode1="use mydatabase;alter table customer ADD email_add VARCHAR(45);" 
>store sqlexec(thisform.zConnHandle,mcode1,'resultcur') to result1
>

>
>unfortunately it doesn't work.