Hi, i'm not entirely sure on what you're askin to do, but i'm kind asure this might help you:
{SELECT A, B, C
FROM table1
WHERE A Is Null
OR A = "xx"
{SELECT A
FROM table1
WHERE A = "yy"
OR A = "zz"
}
}
Hope this helps... I have not failed; I merely found 100,000 different ways of not succeding...