Call now: 252-767-6166  
Oracle Training Oracle Support Development Oracle Apps

 
 Home
 E-mail Us
 Oracle Articles
New Oracle Articles


 Oracle Training
 Oracle Tips

 Oracle Forum
 Class Catalog


 Remote DBA
 Oracle Tuning
 Emergency 911
 RAC Support
 Apps Support
 Analysis
 Design
 Implementation
 Oracle Support


 SQL Tuning
 Security

 Oracle UNIX
 Oracle Linux
 Monitoring
 Remote s
upport
 Remote plans
 Remote
services
 Application Server

 Applications
 Oracle Forms
 Oracle Portal
 App Upgrades
 SQL Server
 Oracle Concepts
 Software Support

 Remote S
upport  
 Development  

 Implementation


 Consulting Staff
 Consulting Prices
 Help Wanted!

 


 Oracle Posters
 Oracle Books

 Oracle Scripts
 Ion
 Excel-DB  

Don Burleson Blog 


 

 

 


 

 

 
 


Display row where count(*) is zero?

Expert Oracle Database Tips by Donald BurlesonSeptember 4, 2015

Question:  I need to write a SQL that counts all rows within a single table using an "in" list, and including all rows counts, even where the row count is zero.  Here is my query:

select
   sts_id,
   count(*) mycount
from
   task
where
   sts_id in (1, 3, 4, 5, 6, 7, 8, 30, 39, 40, 41, 42)
group by sts_id;

sts_id     mycount
-------    -----------
1          48
8           1
39         16
42         76

As you see, I cannot display the rows where the count(*) is zero, and the in list seems to prevent the display of matching rows where the count(*) is zero.  How do I get the rows with zero values to appear in my SQL output?

Answer:  If you were doing this count with a table join, it's easy to invoke an "outer join" to include missing rows, but here you have only a single table. 

Because the "IN" list restricts which rows are selected, values with no row will be displayed unless we create them in a temporary table:

create table in_list (sts_id number);
insert into in_list values (1);
insert into in_list values (3);
 . . . .
insert into in_list values (42);

Now, you can simple use this temporary table in an outer join to include the missing rows, something like this:

select
   in_list.sts_id,
   count(*) mycount
from
   task
left outer join
   in_list

group by sts_id;

Oracle guru Steve Callan offers this PL/SQL solution to displaying rows where count is zero.  He notes that you would need to create a temporary create a table with just those values (and a column for the count) and modify the code to select sts_id from the new table, and update the new table with the count:

If the sts_id values do not exist in task, then create a table with just those values (and a column for the count) and modify the code to select sts_id from the new table, and update the new table with the count. Count will always return a number.

If you have duplicate sts_id values, then you need to account for them as well:

drop table task;
create table task (id number, line number);
insert into task values (1,1);
insert into task values (1,2);
insert into task values (2,null);
commit;
set serveroutput on
declare
  v_cnt integer;
  cursor c is
  select distinct id from task;  
begin
  for r in c loop
    select count(*) into v_cnt
    from task
    where id = r.id
    and line > 0;
    dbms_output.put_line(r.id||' '||v_cnt);
  end loop;
end;
/

 
Get the Complete
Oracle SQL Tuning Information 

The landmark book "Advanced Oracle SQL Tuning  The Definitive Reference"  is filled with valuable information on Oracle SQL Tuning. This book includes scripts and tools to hypercharge Oracle 11g performance and you can buy it for 30% off directly from the publisher.

 

 

Burleson is the American Team

Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications.

Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:  

and include the URL for the page.


                    









Burleson Consulting

The Oracle of Database Support

Oracle Performance Tuning

Remote DBA Services


 

Copyright © 1996 -  2017

All rights reserved by Burleson

Oracle ® is the registered trademark of Oracle Corporation.

Remote Emergency Support provided by Conversational

 

 

��  
 
 
Oracle Training at Sea
 
 
 
 
oracle dba poster
 

 
Follow us on Twitter 
 
Oracle performance tuning software 
 
Oracle Linux poster