How to check if Cursor Expression(select cursor) is returning null?

Question

I've a select cursor expression with multiple inner select cursors. I wanted to check in the outer most select cursor if the inner cursor is returning any value or not. eg.,

SELECT
CURSOR
  (SELECT
   CURSOR
     (SELECT c.cat_name category ,
      CURSOR
        (SELECT
         CURSOR
           (SELECT grp.grpng
            GROUPING ,
                             grp.action_group action_group ,
            CURSOR
              (SELECT
               CURSOR
                 (SELECT header_id ,
                         order_no ,
                         cust_name ,
                         cust_phone ,
                         org ,
                         status `enter code here`,
                         reason
                  FROM headers h
                  WHERE h.header_id = da.header_id ) "G_HEADER"
               FROM dual) "LIST_G_HEADER"
            FROM action_group grp
            WHERE grp.grpng = da.grpng
              AND grp.action_grp = da.action_grp ) "G_ACTION"
         FROM action_rep da
         WHERE da.org = 'test'
           AND da.cat_id = c.cat_id
         ORDER BY category,
         GROUPING,
                  reason ) "LIST_G_ACTION_GROUP"
      FROM dual ) "G_CATEGORY"
   FROM dual ) "LIST_G_CATEGORY" ,
       c.category_name
FROM cat c
ORDER BY c.cat_name

I need to put a check to see if the result of "LIST_G_CATEGORY" cursor is null or not and if it is null then do not display that row. PS: please ignore the column name mismatches as the query is made up in rush to post here.

Version: Oracle 11g R2

Answer 1

In order to check whether the cursor is empty or not , one should fetch it first.

This means that you could crate a function (probably using SYS_REFCURSOR ) that will return 1 or 0 accordingly, when the cursor is empty or not - but you should be aware of the rowtype that the cursor returns, in order to do that.

Check this references

oracle cursor expression ,

similar question on stackoverflow ,

check sys ref cursor is empty - stackoverflw ,

ref cursor rowcount question .