JOIN a table with a grouped by table - sql

Question

I have two tables i am trying to join and do a count on, basically to bring over the date onto the Units table. The problem is that the intakes table has duplicates.
SELECT
Units.Clinic,
Units.display_id,
INTAKES.initial_intake_date,
COUNT(case_note_type_desc) AS CountOfUAs
FROM Units
LEFT JOIN (SELECT display_id,Clinic,initial_intake_date
FROM factIntakesAndDischarges
GROUP BY display_id,Clinic,initial_intake_date ) INTAKES
ON Units.display_id = INTAKES.display_id
AND Units.display_id = INTAKES.Clinic
WHERE casenotes_date BETWEEN '4/9/20' AND '5/9/20'
AND case_note_type_desc = '(UA)'
GROUP BY Units.Clinic,
Units.display_id,
INTAKES.initial_intake_date
ORDER BY CountOfUAs desc,Clinic,display_id,initial_intake_date
This gives me the correct count, but the initial_intake_date comes back NULL. The other join i tried gave me the correct initial_intake_date, but the count was off.

Answer 1

Based on your, I would really expect a query more like this:
SELECT u.Clinic, u.display_id, MIN(i.initial_intake_date) as initial_intake_date,
COUNT(*) AS CountOfUAs
FROM Units u LEFT JOIN
factIntakesAndDischarges fid
ON u.display_id = i.display_id AND
u.display_id = INTAKES.display_id
WHERE u.casenotes_date >= '2020-04-09' AND '2020-05-09' AND
u.case_note_type_desc = '(UA)'
GROUP BY u.Clinic, u.display_id,
ORDER BY CountOfUAs desc, Clinic, display_id, initial_intake_date;
Even if the numbers are not quite right, this is a simpler query for starting to fix.

Answer 2

ON Units.display_id = INTAKES.display_id
AND Units.display_id = INTAKES.Clinic
OR
ON Units.display_id = INTAKES.display_id
AND Units.Clinic = INTAKES.Clinic

Answer 3

WITH UnitsTable AS
(
SELECT
Clinic
, display_id
, CountOfUAs = COUNT(case_note_type_desc)
FROM Units
)
, IntakesTable AS
(
SELECT
display_id
, Clinic
, initial_intake_date
FROM factIntakesAndDischarges
-- I am asuming casenotes_date and casenotes_type_Desc belong to Intakes
-- If not, move this WHERE to UnitsTable above
WHERE
casenotes_date BETWEEN '4/9/20' AND '5/9/20'
AND case_note_type_desc = '(UA)'
GROUP BY
display_id
, Clinic
, initial_intake_date
)
SELECT
U.Clinic
, U.display_id
, I.initial_intake_date
, U.CountOfUAs
FROM UnitsTable U
JOIN IntakesTable I ON I.Display_ID = U.Display_ID
AND I.Clinic = U.Clinic
ORDER BY
U.CountOfUAs desc
, U.Clinic
, U.display_id
, I.initial_intake_date