Show something different insted of "no rows selected"

Question

My aim is quite simple. Show values from var1, var2 and var3 if count(*) is bigger that 0 and show empty strings ' ' where there is no values with meet a condition. I try do this on several ways. Actually my query looks like this below:
WITH cntct AS
  (select CONTACT_NAME as var1, LAST_NAME as var2, FIRST_NAME as var3, CONTACT_PHONE as P from dmo.contact_view)
  select distinct decode(cnt.cntall,0,'',ct.var1) as var1, decode(cnt.cntall,0,'',ct.var2) as var2, decode(cnt.cntall,0,'',ct.var3) as var3, ct.P as P from
  (select count(*) as cntall from cntct) cnt, cntct ct where P = 'not existing value';Can you provide me some idea, what to change to show ' ' if P will be not existing value?

Answer 1

Hi,
lesak wrote:
Of course, you're right. So let's start from begining. My Oracle version is 11.2.0.1.
And what I'm trying to say is that a query from below works great after your remarks:
WITH cntct AS
(select CONTACT_NAME as var1, LAST_NAME as var2, FIRST_NAME as var3, CONTACT_PHONE as P from dmo.contact_view)
select distinct decode(cnt.cntall,0,'',ct.var1) as var1, decode(cnt.cntall,0,'',ct.var2) as var2, decode(cnt.cntall,0,'',ct.var3) as var3, ct.P as P from
(select count(*) as cntall from cntct) cnt left outer join cntct ct on ct.P = 'not existing value';But, when I'm trying to create a view base on that query, Oracle qives me such error:
SQL> CREATE OR REPLACE FORCE VIEW some_view AS
2    WITH cntct AS
3    (select CONTACT_NAME as var1, LAST_NAME as var2, FIRST_NAME as var3, CONTACT_PHONE as P from dmo.contact_view)
4    select distinct decode(cnt.cntall,0,'',ct.var1) as var1, decode(cnt.cntall,0,'',ct.var2) as var2, decode(cnt.cntall,0,'',ct.var3) as var3, ct.P as P from
5    (select count(*) as cntall from cntct) cnt left outer join cntct ct;
(select count(*) as cntall from cntct) cnt left outer join cntct ct
ERROR at line 5:
ORA-00905: missing keyword
If you don't post CREATE TABLE and INSERT statements for contact_view, or use a commonly available table, (such as scciott.emp) in place of contact_view, then I can't reproduce the problem. If contact_view really is a view, you can pretend it's a table, and post CREATE TABLE and INSERT statements that mimic the contents of your real contact_view. Post some sample data for contact_view, and what you want some_view to contain given that data.
I suspect you're getting an error becuase there is jo join condition after the column alias ct at the end of line 5.
I need to create that view, because my final query should look like:
select * from some_view where P = 'existing or not existing value';
If that's your query, then it will return 0 rows (and NOT 1 row containing all NULLs) if P is never equal to the given value. If you want to query table y, and get a row of all NULLs when condition c is never true, then use:
SELECT  y.*
FROM             x
LEFT OUTER JOIN  y  ON c
;where x is an table, view or sub-query that contains exactly 1 row.
Are you trying to create a view based on a parameter (e.g., :target_p := 'existing or not existing value')? Please give a concrete example of what you're trying to do.