How to display required data from emp table?

Question

Hi every one, this is my first post in this portal. I want display the details of emp table.. for that I am using this SQL statement.
select * from emp where mgr=nvl(:mgr,mgr);
when I give the input as 7698 it is displaying the corresponding records... and also when I won't give any input then it is displaying all the records except the mgr with null values.
1)I want to display all the records when I won't give any input including nulls
2)I want to display all the records who's mgr is null
Is there any way to incorporate to include all these in a single query..

Answer 1

Hi,
937440 wrote:
Hi every one, this is my first post in this portal. Welcome to the forum!
Be sure to read the forum FAQ {message:id=9360002}
I want display the details of emp table.. for that I am using this SQL statement.
select * from emp where mgr=nvl(:mgr,mgr);
when I give the input as 7698 it is displaying the corresponding records... and also when I won't give any input then it is displaying all the records except the mgr with null values.
1)I want to display all the records when I won't give any input including nulls
2)I want to display all the records who's mgr is null
Is there any way to incorporate to include all these in a single query..It's a little unclear what you're asking.
The following query always includes rows where mgr is NULL, and when the bind variable :mgr is NULL, it displays all rows:
SELECT  *
FROM     emp
WHERE     LNNVL (mgr != :mgr)
;That is, when :mgr = 7698, it displays 6 rows, and when :mgr is NULL it displays 14 rows (assuming you're using the Oracle-supplied scott.emp table).
The following query includes rows where mgr is NULL only when the bind variable :mgr is NULL, in which case it displays all rows:
SELECT     *
FROM     emp
WHERE     :mgr     = mgr
OR       :mgr       IS NULL
;When :mgr = 7698, this displays 5 rows, and when :mgr is NULL it displays 14 rows.
The following query includes rows where mgr is NULL only when the bind variab;e :mgr is NULL, in which case it displays only the rows where mgr is NULL. That is, it treats NULL as a value:
SELECT     *
FROM     emp
WHERE     DECODE ( mgr
            , :mgr, 'OK'
            )     = 'OK'
;When :mgr = 7698, this displays 5 rows, and when :mgr is NULL, it displays 1 row.