SELECT a.ParcelID, a.PropertyAddress, b.ParcelID, b.PropertyAddress, ifnull(a.PropertyAddress,b.PropertyAddress)
FROM mytable a
join mytable b on a.ParcelID = b.ParcelID
and a.UniqueID <> b.UniqueID
where a.PropertyAddress is null;
update mytable a
join mytable b on a.ParcelID = b.ParcelID
and a.UniqueID <> b.UniqueID
set PropertyAddress = updat
where a.PropertyAddress is null;
Column 'PropertyAddress' in field list is ambiguous' after I run my update statement portion