SQL Selecting rows with not the same condition for all - sql

Question

I have to create SQL query that select persons datas. Every person has several grades and I have to select first by time for everyone. I don't know how do it because conditional is different for every person. Below is my current code which doesn't works.
SELECT s.sol_last_name,
g.grade_name,
MIN(sg.sol_grade_date_from)
FROM [dbo].[dim_s####] AS s
LEFT JOIN [dbo].[fact_s####_grade] AS sg ON s.sol_key = sg.sol_grade_sollers_key
LEFT JOIN [dbo].[dim_grade] AS g ON g.grade_key = sg.sol_grade_grade_key
GROUP BY s.sol_last_name,
g.grade_name
HAVING MIN(sg.sol_grade_date_from) = sg.sol_grade_date_from

Answer 1

You can put the earliest date in a subquery, and then inner join there:
SELECT s.sol_last_name,
g.grade_name,
sg.sol_grade_date_from
FROM [dbo].[dim_s####] AS s
INNER JOIN (
select sol_grade_grade_key
,min(sol_grade_date_from) as sol_grade_date_
from from [dbo].[dim_grade]
GROUP BY sol_grade_grade_key) AS g
ON g.grade_key = sg.sol_grade_grade_key
LEFT JOIN [dbo].[fact_s####_grade] AS sg
ON s.sol_key = sg.sol_grade_sollers_key

Answer 2

Use a Common Table Expression (cte) to save some typing. Then do a NOT EXISTS to return a row only if same sol_last_name has no older grade.
WITH CTE (sol_last_name, grade_name, grade_date_from) AS
(
SELECT s.sol_last_name,
g.grade_name,
sg.sol_grade_date_from
FROM [dbo].[dim_s####] AS s
LEFT JOIN [dbo].[fact_s####_grade] AS sg ON s.sol_key = sg.sol_grade_sollers_key
LEFT JOIN [dbo].[dim_grade] AS g ON g.grade_key = sg.sol_grade_grade_key
)
select sol_last_name, grade_name, grade_date_from
from cte as t1
where not exists (select 1 from cte t2
where t2.sol_last_name = t1.sol_last_name
and t2.grade_date_from < t2.grade_date_from)