T-SQL Case when with Using with Sql Two Column - sql

Question

First of all I would like to thank the friends who helped this complex and difficult query.
I have three tables
Table 1
StaffId FirstName LastName staffType
---------------------------------------
1 Adam Sorme Student
2 Lara Sandra Teacher
3 Jack Jones Student
Table 2
GateId GateName
---------------------------------------
1 frontDoor
2 superDoor
Table 3
Id transitionDate GateId StaffId
---------------------------------------
1 2018-01-1 08:00:00 1 1
2 2018-01-1 10:00:00 2 1
3 2018-01-1 20:00:00 2 1
4 2018-01-2 07:00:00 1 2
5 2018-01-2 10:00:00 1 3
6 2018-01-9 12:00:00 2 2
I want the first and last movements of students for each day. Value must be set to null if no movement is available between the specified dates
transitionDate> '2018-01-1 00:00:00 000'
and transitionDate< '2018-01-03 00:00:00 000'
OUTPUT:
Id Date MinTransitionDate MaxTransitionDate FirstGateName LastGateName StaffId StaffType
1 2018-01-01 2018-01-1 08:00:00 2018-01-1 20:00:00 frontDoor superDoor 1 Student
2 2018-01-01 null null null null 3 student
3 2018-01-02 null null null null 1 student
4 2018-01-02 2018-01-2 10:00:00 null frontDoor null 3 student
The following query is partially working.
select
q.*,
g1.GateName as first_gate_name,
g2.GateName as last_gate_name
from
(
select s.staffId, d.dte,
min(t.transitionDate) as min_Date,
max_Date= case when count(1)>1 then max(t.transitionDate) else null end,
max(case when seqnum_asc = 1 then gateId end) as first_gateid,
max(case when seqnum_desc = 1 then gateId end) as last_gateid
from (select s.* from Staff s where stafftype = 'Student') s cross join
(select distinct cast(transitionDate as date) as dte from Transitions) d left join
(select t.*,
row_number() over (partition by StaffId, cast(transitionDate as date) order by transitionDate) as seqnum_asc,
row_number() over (partition by StaffId, cast(transitionDate as date) order by transitionDate desc) as seqnum_desc
from Transitions t
) t
on cast(t.transitiondate as date) = d.dte and
t.staffId = s.staffId and
1 in (t.seqnum_asc, t.seqnum_desc)
group by s.staffId, d.dte
) q
left join Gates g1 on g1.gateId = q.first_gateid
left join Gates g2 on g2.gateId = q.last_gateid
see working demo
Problem : max_date in 4. row is empty. I want the value of last_gateid to be null. Can you help me?
screenshot 4. row
https://cdn.pbrd.co/images/H7vyu31.png

Answer 1

A quick fix would be replacing this line
max(case when seqnum_desc = 1 then gateId end) as last_gateid
with
max(case when (seqnum_desc = 1 and seqnum_asc != 1) then t.gateId end) as last_gateid

Answer 2

It is obvious that some one helped you write the query and you gave him more explanation of the problem , what i did is tweaking the query you provided and used the same logic to give you the desired output although i would prefer to rewrite it in a more understandable way :
select
q.*,
g1.GateName as first_gate_name,
g2.GateName as last_gate_name
from
(
select s.staffId, d.dte,
min(t.transitionDate) as min_Date,
max_Date= case when count(1)>1 then max(t.transitionDate) else null end,
max(case when seqnum_asc = 1 then gateId end) as first_gateid,
case when count(1)>1 then MAX(gateId) end as last_gateid
from (select s.* from Staff s where stafftype = 'Student') s cross join
(select distinct cast(transitionDate as date) as dte from Transitions) d left join
(select t.*,
row_number() over (partition by StaffId, cast(transitionDate as date) order by transitionDate) as seqnum_asc,
row_number() over (partition by StaffId, cast(transitionDate as date) order by transitionDate desc) as seqnum_desc
from Transitions t
) t
on cast(t.transitiondate as date) = d.dte and
t.staffId = s.staffId and
1 in (t.seqnum_asc, t.seqnum_desc)
group by s.staffId, d.dte
) q
left join Gates g1 on g1.gateId = q.first_gateid
left join Gates g2 on g2.gateId = q.last_gateid

Answer 3

IF OBJECT_ID('dbo.Staff') IS NOT NULL DROP TABLE Staff
create table Staff (StaffId int, FirstName varchar(20), LastName
varchar(20), staffType varchar(20))
insert into Staff values
(1, 'Adam', 'Sorme', 'Student'),
(2, 'Lara', 'Sandra', 'Teacher'),
(3, 'Jack', 'Jones', 'Student')
IF OBJECT_ID('dbo.Gates') IS NOT NULL DROP TABLE Gates
create table Gates (GateId int, GateName varchar(20))
insert into Gates values
(1, 'frontDoor'),
(2, 'backDoor')
IF OBJECT_ID('dbo.Transitions') IS NOT NULL DROP TABLE Transitions
create table Transitions (Id int, transitionDate datetime, GateId int,
StaffId int)
insert into Transitions values
(1, '2018-01-1 08:00:00', 1, 1),
(2, '2018-01-1 10:00:00', 2, 1),
(3, '2018-01-1 20:00:00', 2, 1),
(4, '2018-01-2 07:00:00', 1, 2),
(5, '2018-01-2 10:00:00', 2, 3),
(6, '2018-01-9 12:00:00', 2, 2)
--select * from Transitions
DECLARE #Datefrom DATETIME = '2018-01-01'
DECLARE #DateTo DATETIME = '2018-01-03'
----1. If the transition table itself is not reliable meaning there
--could be imports and the maxID could be for a lesser datetime
IF OBJECT_ID('tempdb..#Transitions') IS NOT NULL DROP TABLE
#Transitions
SELECT *, [GateSortID] = RANK() OVER (PARTITION BY StaffID ORDER BY
StaffID,GateID,TransitionDate)
INTO #Transitions
FROM Transitions
----2.Based on above temp table get first and last dates
IF OBJECT_ID('tempdb..#FirstandLastDates') IS NOT NULL DROP TABLE
#FirstandLastDates
SELECT T.StaffId,
[FirstDate] = FirstDate.transitionDate,
[LastDate] = LastDate.transitionDate
INTO #FirstandLastDates
FROM #Transitions T
JOIN
(
SELECT TT.StaffId,
[MinGateSortID] = MIN(GateSortID),
TT.GateID,
G.transitionDate
FROM #Transitions TT
JOIN Transitions G
ON TT.StaffId = G.StaffId
AND TT.Id = G.ID
AND TT.GateId = G.GateId
WHERE GateSortID = 1-- MIN VALUE WILL ALWAYS BE 1
GROUP BY TT.StaffID,TT.GateID,G.transitionDate
)FirstDate --lol!!
ON T.StaffID= FirstDate.StaffID
LEFT JOIN
(
SELECT TT.StaffId, TT.GateId, G.TransitionDate
FROM #Transitions TT
JOIN #Transitions G
ON TT.StaffId = G.StaffId
AND TT.Id = G.ID
AND TT.GateId = G.GateId
JOIN
(
SELECT StaffID,
[MaxGateSortID] = MAX(GateSortID)
FROM #Transitions TT
WHERE GateSortID <> 1 -- SO THAT IF THE PERSON HAS NOT --CLOCKED OUT YET ONLY CLOCKED IN DO NOT CONSIDER THAT THE
--GATES ARE SAME
GROUP BY StaffID
) LastGate1
ON TT.StaffId = LastGate1.StaffId
AND TT.GateSortID = LastGate1.MaxGateSortID
)LastDate
ON T.StaffId = LastDate.StaffId
GROUP BY T.StaffId,FirstDate.transitionDate,LastDate.transitionDate
----3.Based on above temp table get first and last transition gates
IF OBJECT_ID('tempdb..#FirstandLastGates') IS NOT NULL DROP TABLE
#FirstandLastGates
SELECT T.StaffId,
[FirstGate] = FirstGate.GateName,
[LastGate] = LastGate.GateName
INTO #FirstandLastGates
FROM #Transitions T
JOIN
(
SELECT StaffID,
[MinGateSortID] = MIN(GateSortID),
TT.GateID,
GateName
FROM #Transitions TT
JOIN Gates G
ON TT.GateId = G.GateId
WHERE GateSortID = 1-- MIN VALUE WILL ALWAYS BE 1
--AND TT.transitionDate BETWEEN #Datefrom AND #DateTo
GROUP BY StaffID,TT.GateID,GateName
)FirstGate
ON T.StaffID= FirstGate.StaffID
LEFT JOIN
(
SELECT TT.StaffId, TT.GateId, G.GateName
FROM #Transitions TT
JOIN Gates G
ON TT.GateId = G.GateId
JOIN
(
SELECT StaffID,
[MaxGateSortID] = MAX(GateSortID)
FROM #Transitions TT
WHERE GateSortID <> 1 -- SO THAT IF THE PERSON HAS NOT CLOCKED
-- OUT YET ONLY CLOCKED IN DO NOT CONSIDER THAT THE GATES ARE --SAME
--AND TT.transitionDate BETWEEN #Datefrom AND #DateTo
GROUP BY StaffID
) LastGate1
ON TT.StaffId = LastGate1.StaffId
AND TT.GateSortID = LastGate1.MaxGateSortID
)LastGate
ON T.StaffId = LastGate.StaffId
GROUP BY T.StaffId,FirstGate.GateName,LastGate.GateName
--MAIN OUTPUT
SELECT DISTINCT --t.Id,
--t.transitionDate,
[MinTransitionDate] = D.FirstDate,
[MaxTransitionDate] = D.LastDate,
[FirstGateName] = G.FirstGate,
[LastGateName] = G.LastGate,
T.[StaffId],
S.StaffType
from Staff S
JOIN #Transitions T
ON S.StaffId = T.StaffId
JOIN #FirstandLastDates D
ON T.StaffId = D.StaffId
JOIN #FirstandLastGates G
ON T.StaffId = G.StaffId
GROUP BY t.Id, D.FirstDate, D.LastDate, G.FirstGate,G.LastGate,T.[StaffId],
S.StaffType