The parameter operator for VFP is ?, not @. Try this:

SQLEXEC(nConnectionHandle,"select * from table where;
        table.ssn=?zSearchValue", "CursorName")

>I am trying to use SQL pass through to read a varible - what am I doing wrong:
>
>
>
>Public zSearchValue
>
>zSearchValue="123456789"
>
>SQLEXEC(nConnectionHandle,"select * from table where;
> table.ssn=@zSearchValue", "CursorName")
>
>
>
>Thanks