Oracle_ Null value judgment

Oracle NULL value Test

Compare items	Is null	is NOT NULL	Nvl	Description
Null	True	False	True
Null	True	False	True
' NULL '	False	True	False
' NULL '	False	True	False
' Null '	False	True	False
‘‘	True	False	True
‘ ‘	False	True	False
Trim (")	True	False	True

1, NULL and 0 in Oracle, empty strings, spaces, including null and NULL are also unequal.
2. Null is still the result of the arithmetic operation in Oracle.
3, the processing method has a NVL function, the comparison method is null or is not NULL.
4. Null cannot be indexed, such as SELECT COUNT (null) from dual query result is 0.
5, the null sort is larger than all other types, one can be empty, and the preceding is null data.

Oracle_ Null value judgment