Manipulating NULLS in Teradata

You cannot solve for the value of a null because, by definition, it has no value.
For example, the expression NULL = NULL has no meaning and therefore can never be true.
A query that specifies the predicate WHERE NULL = NULL is not valid because it can never be true.
The meaning of the comparison it specifies is not only unknown, but unknowable.

Examples:
When any component of a value expression is null, then the result is null.

SELECT NULL+10+15

Output: NULL

NULLS with comparison operators:
All the following indicates the wrong usage with NULL
SELECT field FROM table WHERE 2 = NULL
SELECT field FROM table WHERE 2 <> NULL
SELECT field FROM table WHERE NULL = NULL
SELECT field FROM table WHERE NULL <> NULL
SELECT field FROM table WHERE 5 = NULL + 5


Proper Usage:
We should use IS NULL or IS NOT NULL in our search conditions.

Examples:
SELECT name FROM table_emp WHERE id IS NULL

SELECT name FROM table_emp WHERE id IS NOT NULL