I'm trying to simplify my stored procedure and I have one that is only using left join based on the user id that is passed in. If the user id is null, don't do left join, but if it is null, left join it with another table. How should I re-write it ? Thank you
CREATE OR ALTER PROCEDURE [dbo].[GetRoom]
#RoomId UNIQUEIDENTIFIER NULL,
#UserId UNIQUEIDENTIFIER
AS
BEGIN
IF (#UserId IS NULL)
BEGIN
SELECT r.Id, r.DisplayName
FROM Room r
INNER JOIN Game g ON r.GameId = g.Id
INNER JOIN ProfileDuplicated pd ON r.HostedById = pd.Id
WHERE r.Id = #RoomId
END
ELSE
SELECT
r.Id, r.DisplayName,
ru.Description, -- this is coming from the left join table
ru.Tags -- from left join table
FROM Room r
INNER JOIN Game g ON r.GameId = g.Id
INNER JOIN ProfileDuplicated pd ON r.HostedById = pd.Id
LEFT JOIN RoomUser ru ON ru.RoomId = r.Id
WHERE r.Id = #RoomId AND ru.UserId = #UserId
END
Currently your stored procedure return different number columns depending on the #UserId.
You may remove the IF condition, and combined it as one single query by moving ru.UserId = #UserId to ON condition. This will make it a true LEFT JOIN to table RoomUser.
This will means it always return 4 columns as result
SELECT r.Id,
r.DisplayName,
ru.Description,
ru.Tags
FROM Room r
INNER JOIN Game g ON r.GameId = g.Id
INNER JOIN ProfileDuplicated pd ON r.HostedById = pd.Id
LEFT JOIN RoomUser ru ON ru.RoomId = r.Id
AND ru.UserId = #UserId
WHERE r.Id = #RoomId
Try something like below,
SELECT
r.Id, r.DisplayName,
ru.Description, -- this is coming from the left join table
ru.Tags -- from left join table
FROM Room r
INNER JOIN Game g ON r.GameId = g.Id
INNER JOIN ProfileDuplicated pd ON r.HostedById = pd.Id
LEFT JOIN RoomUser ru ON ru.RoomId = r.Id
AND r.Id IS NOT NULL
AND r.Id = #RoomId
AND ru.UserId IS NOT NULL
AND ru.UserId = #UserId
You can use ISNULL function to check the NULL value of the parameter. (Assuming ru.userId will not be NULL)
WHERE r.Id = #RoomId AND
ru.UserId = ISNULL(#UserId, ru.UserId)
Related
I want ensure none of the tables included through INNER JOIN return 0 rows, resulting in an empty result-set due to the join being INNER. I want to be able to return information to the user about which table had no records, causing the query to return empty.
PS: Please ignore Foreign Keys for this question.
Example-query:
SELECT * FROM Person P
INNER JOIN [User] U ON U.PersonId = P.Id
INNER JOIN Email E ON E.UserId = U.Id
INNER JOIN Company C on C.Id = U.CompanyId
WHERE P.Id = 3
Let's say the user had no associated Email-records. I then want to be able to tell the user about this. Note: I only need to print the first failing step, I.E if the user has no Email and no Company, I only need to tell the user about him not having any Email.
How I would have solved it earlier:
I would perform the complete query in steps, building it up join by join, doing a whole lot of redundant querying. I really don't like this solution at all, which is why I'm asking for help.
-- Ensure Person exists
IF NOT EXISTS (
SELECT * FROM Person P
WHERE P.Id = 3
)
BEGIN
PRINT 'No associated Person was found';
RETURN 1;
END
-- Ensure User exists
IF NOT EXISTS (
SELECT * FROM Person P
INNER JOIN [User] U ON U.PersonId = P.Id
WHERE P.Id = 3
)
BEGIN
PRINT 'No associated User was found';
RETURN 1;
END
And so on. How can I write this more concise, in a way that solves the same problem but avoids repeating queries?
Thanks in advance.
Update
By looking at the answers, I realized my example was bad. Using LEFT JOIN is ok in this example, since the "join-chain" is not straight; Person joins User, then User joins in multiple directions, like this:
Person - User - Email
|
Company
I'll try to provide a different example:
SELECT * FROM a
INNER JOIN b ON b.a_id = a.id
INNER JOIN c ON c.b_id = b.id
INNER JOIN d ON d.c_id = c.id
INNER JOIN e ON e.d_id = d.id
INNER JOIN f ON f.e_id = e.id
INNER JOIN g ON g.f_id = f.id
The join-chain would then look like this:
a - b - c - d - e - f - g
If I were to use LEFT JOIN's to ensure existence of records, the IIF/CASE statements would get pretty terrible. Example:
SELECT
CASE WHEN b.id is null THEN 'b is null' END as b_is_null
CASE WHEN b.id is not null and c.id is null THEN 'b is null' END as c_is_null
..
CASE WHEN b.id is not null and c.id is not null and d.id is not null and e.id is not null and f.id is not null and g.id is null THEN 'g is null' AS g_is_null
FROM a
LEFT JOIN b ON b.a_id = a.id
LEFT JOIN c ON c.b_id = b.id
LEFT JOIN d ON d.c_id = c.id
LEFT JOIN e ON e.d_id = d.id
LEFT JOIN f ON f.e_id = e.id
LEFT JOIN g ON g.f_id = f.id
It can get really ugly. And these examples are with 1-character alias-names and 2-character property-names.
Keep in mind, I also want to check if the first table (Person/a, the one not joined) also returns rows.
You need to use left join. From your query, if a person doesn't have any user they obviously doesn't have any email or company. So all left join will be fine.
SELECT P.*,
IIF(U.PersonID IS NULL, 0, 1) AS isUserExists,
IIF(E.UserId IS NULL, 0, 1) AS isEmailExists,
IIF(C.Id IS NULL, 0, 1) AS isCompanyInformationExists
FROM Person P
LEFT JOIN [User] U ON U.PersonId = P.Id
LEFT JOIN Email E ON E.UserId = U.Id
LEFT JOIN Company C on C.Id = U.CompanyId
WHERE P.Id = 3
If U.PersonID IS NULL then no user existed, if E.UserId IS NULL then no email existed, if C.Id IS NULL then no company information existed for that person. By this you can use your messages as you need.
Use case statements like below and print your message.
select
case when u.PersonId is null and p.id is not null then 'user not exists'
WHEN u.PersonId IS NOT NULL AND p.id IS NOT NULL AND e.mailid is null THEN 'mail id not exist'
else 'No associated Person was found' end message
FROM Person P
left JOIN [User] U ON U.PersonId = P.Id
left JOIN Email E ON E.UserId = U.Id
left JOIN Company C on C.Id = U.CompanyId
WHERE P.Id = 3
DECLARE #Email VARCHAR(50)
DECLARE #Company VARCHAR(50)
SELECT #Email = E.Email, #Company = C.CompanyName FROM Person P
INNER JOIN [User] U ON U.PersonId = P.Id
LEFT JOIN Email E ON E.UserId = U.Id
LEFT JOIN Company C on C.Id = U.CompanyId
WHERE P.Id = 3
IF #Email IS NULL
Print 'NO Email'
IF #Company IS NULL
Print 'No Company'
I probably messed that title up! So I have a column called "programID" and I want another column to tell me the most recent date an order was placed using the programID. I think I'd need a subcolumn but the problem is how do I use the row's programID so that it matches the programID for the same row?
DECLARE #ClientIDs varchar(4) = 6653;
DECLARE #ProgramStatus char(1) = 'Y'; -- Y, N, or R
SELECT
rcp.RCPID AS ProgramID
, rcp.RCPName AS Program
, rcp.RCPActive AS ProgramStatus
, aa.AACustomCardInternalReview AS VCCP
, aa.AAJobNo AS AAJobNo
, aas.AASName AS AAStatus
, rcp.RCPOpsApproved AS OpsApproved
, clt.CltID AS ClientID
, rcp.RCPSignatureRequired AS SignatureRequired
, st.STEnumValue AS DefaultShipType
, rcp.RCPShipMethodOverrideType AS ShipTypeOverride
,aa.AANetworkProgramID
,(Select max(cdconfirmationdate) from carddet where ) --can't figure this part out
FROM
RetailerCardProgram rcp WITH (NOLOCK)
INNER JOIN ClientRetailerMap crm WITH (NOLOCK)
ON crm.CRMRetailerID = rcp.RCPRetailerID
INNER JOIN Client clt WITH(NOLOCK)
ON clt.CltID = crm.CRMCltID
LEFT JOIN AssociationApproval aa WITH (NOLOCK)
ON aa.AARetailerID = rcp.RCPRetailerID
AND aa.AABin = rcp.RCPBin6
AND aa.AAFrontOfPlasticTemplateID = rcp.RCPFOCTemplateID
AND aa.AABackOfPlasticTemplateID = rcp.RCPBOCTemplateID
AND ISNULL(aa.AACardID, 0) = ISNULL(rcp.RCPDefaultPlasticCardID, 0)
-- AND LOWER(rcp.RCPName) NOT LIKE '%do not use%' -- Needed for AA Job Number 1594
LEFT JOIN AssociationApprovalStatus aas WITH (NOLOCK)
ON aas.AASID = aa.AAAssociationApprovalStatusID
LEFT JOIN OpenLoopAssociation ola WITH (NOLOCK)
ON ola.OLAID=rcp.RCPOLAID
LEFT JOIN ClientCardProgramMap ccpm WITH (NOLOCK)
ON ccpm.CCPMCardProgramID = rcp.RCPID
AND ccpm.CCPMClientID = clt.CltID
LEFT JOIN TippingModule tm WITH (NOLOCK)
ON tm.TMid = rcp.RCPTippingModuleID
LEFT JOIN GiftCardTemplate fgt WITH (NOLOCK)
ON fgt.gtid = rcp.RCPFOCTemplateID
AND fgt.GTPage='P'
LEFT JOIN GiftCardTemplate bgt WITH (NOLOCK)
ON bgt.gtid = rcp.RCPBOCTemplateID
AND bgt.GTPage='PB'
LEFT JOIN Card c WITH (NOLOCK)
ON c.CardID = rcp.RCPDefaultCarrierID
LEFT JOIN CardType ct WITH (NOLOCK)
ON ct.CTID = c.CardTypeID
LEFT JOIN RetailerCardProgramTCSheetMap rtm1 WITH (NOLOCK)
ON rtm1.RTMRCPID = rcp.RCPID
AND rtm1.RTMInsertOrder = 1
LEFT JOIN RetailerCardProgramTCSheetMap rtm2 WITH (NOLOCK)
ON rtm2.RTMRCPID = rcp.RCPID
AND rtm2.RTMInsertOrder = 2
LEFT JOIN RetailerCardProgramTCSheetMap rtm3 WITH (NOLOCK)
ON rtm3.RTMRCPID = rcp.RCPID
AND rtm3.RTMInsertOrder = 3
LEFT JOIN RetailerCardProgramTCSheetMap rtm4 WITH (NOLOCK)
ON rtm4.RTMRCPID = rcp.RCPID
AND rtm4.RTMInsertOrder = 4
LEFT JOIN TCSheet i1 WITH (NOLOCK)
ON i1.TCSID = rtm1.RTMTCSID
LEFT JOIN TCSheet i2 WITH (NOLOCK)
ON i2.TCSID = rtm2.RTMTCSID
LEFT JOIN TCSheet i3 WITH (NOLOCK)
ON i3.TCSID = rtm3.RTMTCSID
LEFT JOIN TCSheet i4 WITH (NOLOCK)
ON i4.TCSID = rtm4.RTMTCSID
LEFT JOIN ShipType st WITH (NOLOCK)
ON st.STId = rcp.RCPDefaultShipTypeID
WHERE
clt.CltID IN (#ClientIDs) -- 6653 and 6657.
AND rcp.RCPActive IN (#ProgramStatus)
ORDER BY
AAJobNo
, Program
You want to join with a nested select on the table carddet. I'm inferring that RCPID is the relationship between carddet and your main table RetainerCardProgram...
SELECT rcp.RCPID AS ProgramID,
date.MAXDATE AS MaxDate,
rest of your columns...
FROM RetailerCardProgram rcp WITH (NOLOCK)
INNER JOIN (
SELECT RCPID, MAX(cdconfirmationdate) as 'MAXDATE'
FROM carddet
GROUP BY RCPID
) date on date.RCPID = rcp.RCPID
rest of query...
You may want a left join if not all IDs have a date in carddet.
Obligatory addition: Also your use of NOLOCK is a bit terrifying. See http://blogs.sqlsentry.com/aaronbertrand/bad-habits-nolock-everywhere/
I have the three tables following in my SQL Server 2008 database:
Cars
Drivers
UnavailableDrivers
What I want is to show unavailableDrivers to the end users if they set #isAvailable = 0. On the other hand, if isAvailable=1, then the end user should see only available drivers. Finally, if isAvailable is NULL then the user should see all the drivers.
declare #isAvailable bit;
I need to write a query like that:
Select *
From Cars c
Inner join Drivers d on (c.driverId = d.Id)
CASE
WHEN #isAvailable = 0 THEN inner join UnavailableDrivers uc on (c.driverId= uc.Id)
WHEN #isAvailable = 1 THEN inner join UnavailableDrivers uc on (c.driverId != uc.Id)
ELSE #IsAvailable END
-- ELSE -> basically DO NOT JOIN UnavailableDrivers
It is giving incorrect syntax error and I couldn't find the right syntax for a few hours unfortunately. Actually I don't feel the query is right either. So any help to fix my query on this logic would be appreciated!
The following query do you want:
SELECT *
FROM Cars c
INNER JOIN Drivers d ON (c.driverId = d.Id)
WHERE (#isAvailable IS NULL) -- will not join to UnavailableDrivers is isAvailable is null
OR (#isAvailable = 0 AND c.driverId IN (SELECT uc.id FROM UnavailableDrivers uc)) -- will join to UnavailableDrivers only if isAvailable equals to 0
OR (#isAvailable = 1 AND c.driverId NOT IN (SELECT uc.id FROM UnavailableDrivers uc)) -- will join to UnavailableDrivers because isAvailable equals to 1
Terrible approach, but you asked for it
USE [DB]
GO
CREATE PROCEDURE [GetDrivers]
#isAvailable bit
AS
BEGIN
IF (#isAvailable = 0)
BEGIN
Select * From Cars c
Inner join Drivers d on (c.driverId = d.Id)
inner join UnavailableDrivers uc on (c.driverId= uc.Id)
END
ELSE
begin
Select * From Cars c
Inner join Drivers d on (c.driverId = d.Id)
inner join UnavailableDrivers uc on (c.driverId!= uc.Id)
end
END
SELECT
*
, CASE
WHEN d.DriverId IS NOT NULL THEN 'Availible'
WHEN u.DriverId IS NOT NULL THEN 'Unavailible'
ELSE 'Driver is in both'
AS 'Driver Status'
FROM Cars c
LEFT JOIN Drivers d
ON c.DriverId = d.DriverId
LEFT JOIN UnavailableDrivers u
ON u.DriverId = c.DriverId
I am trying to retrieve the right count of records to mitigate an issue I am having. The below query returns 327 records from my database:
SELECT DISTINCT COUNT(at.someid) AS CountOfStudentsInTable FROM tblJobSkillAssessment AS at
INNER JOIN tblJobSkills j ON j.jobskillid = at.skillid
LEFT JOIN tblStudentPersonal sp ON sp.someid2 = at.someid
INNER JOIN tblStudentSchool ss ON ss.monsterid = at.someid
INNER JOIN tblSchools s ON s.schoolid = ss.schoolid
INNER JOIN tblSchoolDistricts sd ON sd.schoolid = s.schoolid
INNER JOIN tblDistricts d ON d.districtid = sd.districtid
INNER JOIN tblCountySchools cs ON cs.schoolid = s.schoolid
INNER JOIN tblCounties cty ON cty.countyid = cs.countyid
INNER JOIN tblRegionUserRegionGroups rurg ON rurg.districtid = d.districtid
INNER JOIN tblGroups g ON g.groupid = rurg.groupid
WHERE ss.graduationyear IN (SELECT Items FROM FN_Split(#gradyears, ',')) AND sp.optin = 'Yes' AND g.groupname = #groupname
Where I run into trouble is trying to reconcile that with the below query. One is for showing just a count of all the particular students the other is showing pertinent information for a set of students as needed but the total needs to be the same and it is not. The below query return 333 students - the reason is because the school the student goes to is in two separate counties and it counts that student twice. I can't figure out how to fix this.
SELECT DISTINCT #TableName AS TableName, d.district AS LocationName, cty.county AS County, COUNT(DISTINCT cc.monsterid) AS CountOfStudents, d.IRN AS IRN FROM tblJobSkillAssessment AS cc
INNER JOIN tblJobSkills AS c ON c.jobskillid = cc.skillid
INNER JOIN tblStudentPersonal sp ON sp.monsterid = cc.monsterid
INNER JOIN tblStudentSchool ss ON ss.monsterid = cc.monsterid
INNER JOIN tblSchools s ON s.schoolid = ss.schoolid
INNER JOIN tblSchoolDistricts sd ON sd.schoolid = s.schoolid
INNER JOIN tblDistricts d ON d.districtid = sd.districtid
INNER JOIN tblCountySchools cs ON cs.schoolid = s.schoolid
INNER JOIN tblCounties cty ON cty.countyid = cs.countyid
INNER JOIN tblRegionUserRegionGroups rurg ON rurg.districtid = d.districtid
INNER JOIN tblGroups g ON g.groupid = rurg.groupid
WHERE ss.graduationyear IN (SELECT Items FROM FN_Split(#gradyears, ',')) AND sp.optin = 'Yes' AND g.groupname = #groupname
GROUP BY cty.county, d.IRN, d.district
ORDER BY LocationName ASC
If you just want the count, then perhaps count(distinct) will solve the problem:
select count(distinct at.someid)
I don't see what at.someid refers to, so perhaps:
select count(distinct cc.monsterid)
I am having an issue with an inner join. It executes but when I pass the value to it, it returns nothing.
CREATE PROCEDURE s_Get$Subject$For$Edit
(
#SubjectID int
)
as
select s.SubjectID, s.SubjectName, s.SubjectDescription, i.QuizID, i.GameID, i.VideoID, q.QuizID, q.QuizName, g.GameID, g.GameName,
v.VideoID, v.VideoName
from [Subjects] s
inner join [SubjectInfo] i on i.SubjectID = s.SubjectID
inner join [Quiz] q on q.QuizID = i.QuizID
inner join [Games] g on g.GameID = i.GameID
inner join [Video] v on v.VideoID = i.VideoID
where s.SubjectID = #SubjectID
What am I missing or overlooking?