Validating null value in oracle sql dating for non singles
' to test for NULL because all comparisons to NULL return NULL.
To compare something against NULL you need to use the special operators IS NULL or IS NOT NULL which are there for precisely this purpose.
Yet humans do need to deal with nulls, and they have the ability to ask questions that the database server cannot. Or does it mean that a value would be applicable, but we simply don't know that value?
The NVL(), IFNULL(), and COALESCE() functions can also be used to achieve the same result.
A field with a NULL value is a field with no value.
One of the most mindboggling values in the Oracle database is the NULL value. In the one before it, it was possible to convert 2 to a varchar2 value.
Examples: NVL(‘A’,’B’) results in A NVL(NULL,’B’) results in B NVL(1,2) results in 1 NVL(NULL,2) results in 2 NVL(‘A’,2) results in A NVL(1, ‘B’) results in an error The last example results in an error because ‘B’ cannot be converted to a number.
I m using multiple inner joins with the same table where an input parameter value is checked within each inner join.