You can use IS NULL/IS NOT NULL On your original table: If the column is defined as NOT NULL, you won't get NULL If the column can have NULL, then, blank string is NULL (Oracle does the conversion for a really long time) You can also use nvl function, but may not be what you really want.
this is clear, I am not familiar with oracle, hehe
【在 M*****r 的大作中提到】 : You can use IS NULL/IS NOT NULL : On your original table: : If the column is defined as NOT NULL, you won't get NULL : If the column can have NULL, then, blank string is NULL (Oracle does the : conversion for a really long time) : You can also use nvl function, but may not be what you really want.