Need help with group by query with condition

Question

Name
ID
A1
1
A2
1
A3
1
A1
1
A2
2
A2
3
A3
3
A1
4
A2
4
A3
5
I want to get result of total count  where ID is less than 4
A1 - 2
A2 - 3
A3 -  2

Answer 1

Hi,
If you want to get 0 counts for names that don't have any low ids, then use a CASE expression instead of a WHERE clause.
You didn't post CREATE TABLE and INSERT statements for your sample data, so I'll use scott.emp to illustrate.
Say you want to see how many sals in each job are under 3000, like this:
JOB       UNDER_3_CNT
CLERK               4
SALESMAN            4
PRESIDENT           0
MANAGER             3
ANALYST             0
Here's one way to do that:
SELECT    job
,         COUNT (CASE WHEN sal < 3000 THEN 1 END)  AS under_3_cnt
FROM      scott.emp
GROUP BY  job
This shows that there are ANALYSTs and PRESIDENTs in the scott.emp table; there just don't happen to be any with sals under 3000.