Question

I have this odd case where I’d like to display all list values with i.e. counter
My test table content

name, misc
A, blah
B, 123
A, asd

now, this query will fetch results just for A and B, but how can I display C “results”

select name, count(*) from table 
where name in ('A','B','C')

result I’d like to get

A 2
B 1
C 0

this case is driving me mad for a day already.
please help

Cheers,
Dan

Answer 1

I think you’ll have to use an outer join for this type of query, such as:

WITH mylist AS (SELECT 'A' name FROM DUAL
                UNION ALL SELECT 'B' FROM DUAL
                UNION ALL SELECT 'C' FROM DUAL)
SELECT l.name, COUNT(t.name)
  FROM mylist l
  LEFT JOIN mytable t ON l.name = t.name
 GROUP BY l.name

You could use a table object instead of a UNION ALL:

CREATE TYPE name_list_t AS TABLE OF VARCHAR2(30);
/

SELECT l.name, COUNT(t.name)
  FROM (SELECT column_value name FROM TABLE(name_list_t('A', 'B', 'C')) l
  LEFT JOIN mytable t ON l.name = t.name
 GROUP BY l.name