SQL query to get the employee who has not been appraised - sql

Question

There is a employees salary history table, sal_hist which has id,name, salary and effective_date. Requirement is to get the employee who has not been appraised. Below is the table:
Id
name
salary
date
1
a
1000
10-5-2020
1
a
2000
12-6-2020
1
a
3000
12-7-2020
2
b
2500
12-5-2020
2
b
3500
12-7-2020
3
c
2500
12-5-2020
Below is the query I have:
Select id,name from sal_hist group by id,name having count(1)=1;
Is there a different way to achieve the result?

Answer 1

If your date column is the appraisal date and you want the user who has not got an appraisal at the latest date then:
SELECT id, name, salary, appraisal_date
FROM (
SELECT s.*,
MAX(appraisal_date) OVER (PARTITION BY id) AS max_user_appraisal_date,
MAX(appraisal_date) OVER () AS max_appraisal_date
FROM salary_history s
)
WHERE appraisal_date = max_user_appraisal_date
AND max_user_appraisal_date < max_appraisal_date
Which, for the sample data:
CREATE TABLE salary_history (Id, name, salary, appraisal_date) AS
SELECT 1, 'a', 1000, DATE '2020-05-10' FROM DUAL UNION ALL
SELECT 1, 'a', 2000, DATE '2020-06-12' FROM DUAL UNION ALL
SELECT 1, 'a', 3000, DATE '2020-07-12' FROM DUAL UNION ALL
SELECT 2, 'b', 2500, DATE '2020-05-12' FROM DUAL UNION ALL
SELECT 2, 'b', 3500, DATE '2020-07-12' FROM DUAL UNION ALL
SELECT 3, 'c', 2500, DATE '2020-05-12' FROM DUAL;
Outputs:
ID
NAME
SALARY
APPRAISAL_DATE
3
c
2500
12-MAY-20
db<>fiddle here

Answer 2

If you are looking for another way to achieve the result and find the employee with only 1 salary listed (no appraisals in the past) you can use a subquery like this:
SELECT id, name
FROM (
SELECT id, name, COUNT(id) AS [count]
FROM sal_hist
GROUP BY id,name)
WHERE count=1;
But I would note that using HAVING as you have currently is a better method.