SQL Server query slow - how do optimize it? - sql

Question

I would like some help to optimize this query to be faster.
This query produces a view that latter will be showed in a table in a website.
This query is slow, and I am trying to make it faster.
The only thing I tried till now is to reduce the amount of columns I retrieve for the table.
This is the query:
SELECT TOP (100) PERCENT Id, MAX(BusinessTitle) AS BusinessTitle, MAX(ClientName) AS ClientName, MAX(ClientType) AS Type, MAX(CreatedWhen) AS CreatedWhen, MAX(CASE WHEN C.[CreatedBy] IS NULL
THEN 'Client' ELSE 'Admin' END) AS CreatedBy, CAST(MAX(CASE WHEN C.IsDisabled = 1 THEN 1 ELSE 0 END) AS BIT) AS IsDisabled, MAX(ReferenceSource) AS ReferenceSource, MAX(OtherReferenceSource)
AS OtherReferenceSource, MAX(Address) AS Address,
(SELECT MAX(T.FirstName + ' ' + T.LastName) AS Expr1
FROM dbo.ApplicationUsers AS A INNER JOIN
dbo.Therapists AS T ON A.UserName = MAX(C.ClientName) AND A.Id = T.ApplicationUserId) AS ClientAdmin,
(SELECT MAX(A.Email) AS Expr1
FROM dbo.ApplicationUsers AS A INNER JOIN
dbo.Therapists AS T ON A.UserName = MAX(C.ClientName) AND A.Id = T.ApplicationUserId) AS Email,
(SELECT MAX(Name) AS Expr1
FROM dbo.Cities AS CY
WHERE (Id = MAX(C.CityId))) AS City,
(SELECT COUNT(*) AS Expr1
FROM dbo.Patients AS P
WHERE (ClientId = C.Id)) AS TotalPatientCount,
(SELECT COUNT(*) AS Expr1
FROM dbo.Patients AS P
WHERE (ClientId = C.Id) AND (IsDeleted = 0) AND (IsDisabled = 0)) AS ActivePatientCount,
(SELECT MAX(CreatedWhen) AS Expr1
FROM dbo.Patients AS P
WHERE (ClientId = C.Id)) AS LastPatientAddition,
(SELECT COUNT(*) AS Expr1
FROM dbo.Treatments AS T
WHERE (ClientId = C.Id)) AS TotalTreatmentCount,
(SELECT MAX(CreatedWhen) AS Expr1
FROM dbo.Treatments AS T
WHERE (ClientId = C.Id)) AS LastTreatmentAddition,
(SELECT COUNT(*) AS Expr1
FROM dbo.Therapists AS T
WHERE (ClientId = C.Id)) AS TotalTherapistCount,
(SELECT COUNT(*) AS Expr1
FROM dbo.Therapists AS T INNER JOIN
dbo.ApplicationUsers AS A ON T.ClientId = C.Id AND T.ApplicationUserId = A.Id
WHERE (A.IsDeleted = 0) AND (A.IsDisabled = 0)) AS ActiveTherapistCount,
(SELECT MAX(A.CreatedWhen) AS Expr1
FROM dbo.Therapists AS T INNER JOIN
dbo.ApplicationUsers AS A ON T.ClientId = C.Id AND T.ApplicationUserId = A.Id) AS LastTherapistAddition,
(SELECT MAX(A.LastLoginDate) AS Expr1
FROM dbo.Therapists AS T INNER JOIN
dbo.ApplicationUsers AS A ON T.ClientId = C.Id AND T.ApplicationUserId = A.Id
WHERE (A.LastLoginDate IS NOT NULL)) AS TherapistLastLoginDate, CAST((CASE WHEN
((SELECT COUNT(S.[Id])
FROM [dbo].[ClientSubscriptions] AS S
WHERE ((S.[ClientId] = C.[Id]) AND (S.[IsDeleted] = 0) AND ((S.[SubscriptionEnd] IS NULL) OR
(S.[SubscriptionEnd] > GETDATE())))) > 0) THEN 1 ELSE 0 END) AS BIT) AS HasActiveSubscription,
(SELECT MAX(SubscriptionEnd) AS Expr1
FROM dbo.ClientSubscriptions AS S
WHERE (ClientId = C.Id) AND (IsDeleted = 0) AND (SubscriptionEnd IS NULL OR
SubscriptionEnd > GETDATE())) AS LastValidSubscriptionEnd, CAST((CASE WHEN
((SELECT COUNT(S.[Id])
FROM [dbo].[ClientSubscriptions] AS S
WHERE ((S.[ClientId] = C.[Id]) AND (S.[IsDeleted] = 0) AND ((S.[SubscriptionEnd] IS NULL) OR
(S.[SubscriptionEnd] > GETDATE())) AND (S.[Id] <>
(SELECT MIN(S2.[Id])
FROM [dbo].[ClientSubscriptions] AS S2
WHERE ((S2.[ClientId] = C.[Id]) AND (S2.[IsDeleted] = 0)))))) > 0) THEN 1 ELSE 0 END) AS BIT) AS IsPayingCustomer, COALESCE
((SELECT MAX(MonthlyPrice) AS Expr1
FROM dbo.ClientSubscriptions AS S
WHERE (ClientId = C.Id) AND (IsDeleted = 0) AND (SubscriptionEnd IS NULL OR
SubscriptionEnd > GETDATE()) AND (MonthlyPrice > 0)), 0.00) AS ActiveSubscriptionMonthlyPrice, MAX(ClientStatus) AS Status, MAX(Phone1) AS Phone, MAX(Phone2) AS Phone2,
(SELECT Code
FROM dbo.DiscountCoupons AS DC
WHERE (Code =
(SELECT TOP (1) DiscountCouponCode
FROM dbo.ClientPayments AS CP
WHERE (ClientId = C.Id)
ORDER BY Id))) AS DiscountCouponCode,
(SELECT IssuedTo
FROM dbo.DiscountCoupons AS DC
WHERE (Code =
(SELECT TOP (1) DiscountCouponCode
FROM dbo.ClientPayments AS CP
WHERE (ClientId = C.Id)
ORDER BY Id))) AS DiscountCouponIssuedTo,
(SELECT ClientDiscount
FROM dbo.DiscountCoupons AS DC
WHERE (Code =
(SELECT TOP (1) DiscountCouponCode
FROM dbo.ClientPayments AS CP
WHERE (ClientId = C.Id)
ORDER BY Id))) AS DiscountCouponClientDiscount, COALESCE
((SELECT COUNT(Id) AS Expr1
FROM dbo.ClientFiles AS F
WHERE (ClientId = C.Id)), 0) AS TotalFilesCount, COALESCE
((SELECT SUM(FileSize) AS Expr1
FROM dbo.ClientFiles AS F
WHERE (ClientId = C.Id)), 0) / 1048576.0 AS TotalFilesSize, CAST(MAX(CASE WHEN C.CrmEnded = 1 THEN 1 ELSE 0 END) AS BIT) AS CrmEnded, MAX(CrmStatus) AS CrmStatus, MAX(CrmUnuseReason)
AS CrmUnuseReason,
(SELECT COUNT(1) AS Expr1
FROM dbo.Tipulog_Crm_Calls_new AS CC
WHERE (Cust_id = C.Id)) AS CrmCallCount
FROM dbo.Clients AS C
WHERE (IsDeleted = 0)
GROUP BY Id

Answer 1

I will add a second answer, which is the complete sql. This has of course not been tested as we have no access to your data, but I think you should be able to debug it yourself. There are many pointers in this code that should show you how to go.
The basic thing is to take out all of the correlated queries and put them as subqueries. The only reason to do this is all the Max/Min you use - I would look at those as if they are not necessary depending on your data then you should take them out and join to the tables directly. All the subqueries are left joins - again make them normal joins if you can depending on your data.
Also took out the outside group by Id, as 99% sure this is not necessary, as is the Top 100% bit.
SELECT BusinessTitle, ClientName, ClientType AS Type, CreatedWhen,
CASE WHEN C.[CreatedBy] IS NULL THEN 'Client' ELSE 'Admin' END) AS CreatedBy,
CAST(CASE WHEN C.IsDisabled = 1 THEN 1 ELSE 0 END AS BIT) AS IsDisabled,
ReferenceSource, OtherReferenceSource, Address,
ApplicationByName.FullName AS ClientAdmin,
ApplicationByName.Email AS Email,
Cities.Name AS City,
Patients.TotalPatientCount,
Patients.ActivePatientCount,
Patients.LastPatientAddition,
Treatments.TotalTreatmentCount,
Treatments.LastTreatmentAddition,
Therapists.TotalTherapistCount,
Therapists.ActiveTherapistCount,
Therapists.LastTherapistAddition,
Therapists.TherapistLastLoginDate
CAST(CASE WHEN Subscriptions.SubscriptionCount>0 then 1 else 0 end as BIT) as HasActiveSubscription,
Subscriptions.LastValidSubscriptionEnd
CAST(Subscriptions.IsPayingCustomer AS BIT) AS IsPayingCustomer,
COALESCE(ActiveSubscriptionMonthlyPrice,0) as ActiveSubscriptionMonthlyPrice
ClientStatus AS Status, Phone1 AS Phone, Phone2 AS Phone2,
ClientPayments.DiscountCouponCode,
DiscountCoupons.IssuedTo AS DiscountCouponIssuedTo,
DiscountCoupons.ClientDiscount AS DiscountCouponClientDiscount,
COALESCE(ClientFiles.TotalFilesCount,0) AS TotalFilesCount,
COALESCE(ClientFiles.TotalFilesSize,0) AS TotalFilesSize,
CAST((CASE WHEN C.CrmEnded = 1 THEN 1 ELSE 0 END) AS BIT) AS CrmEnded,
CrmStatus, CrmUnuseReason,
Crm_Calls.CrmCallCount
FROM dbo.Clients AS C
left join (
select A.UserName,
max(T.FirstName + ' ' + T.LastName) as FullName,
max(A.Email) as Email
from dbo.ApplicationUsers A
join dbo.Therapists T on T.ApplicationUserId=A.Id
group by A.Username
) ApplicationByName on ApplicationByName.UserName=C.ClientName
join dbo.Cities on Cities.ID=c.CityID
left join (
SELECT ClientId,
COUNT(*) AS TotalPatientCount,
sum(case when IsDeleted = 0 AND IsDisabled = 0 then 1 else 0 end) AS ActivePatientCount,
MAX(CreatedWhen) AS LastPatientAddition
FROM dbo.Patients
GROUP BY ClientId
) Patients on Patients.ClientId = C.Id
left join (
SELECT ClientId,
COUNT(*) AS TotalTreatmentCount,
MAX(CreatedWhen) AS LastTreatmentAddition
FROM dbo.Treatments
GROUP BY ClientId
) Treatments on Treatments.ClientID = C.Id
left join (
select T.ClientId,
count(distinct T.Id) as TotalTherapistCount,
sum(case when A.IsDeleted = 0 AND A.IsDisabled = 0 then 1 else 0 end) as ActiveTherapistCount,
max(A.CreatedWhen) as LastTherapistAddition,
max(A.LastLoginDate) as TherapistLastLoginDate
from Therapists T
left join dbo.ApplicationUsers A on A.Id=T.ApplicationUserId
group by T.ClientId
) Therapists on Therapists.ClientID = C.Id
left join (
SELECT S.ClientId,
count(*) as SubscriptionCount,
MAX(SubscriptionEnd) as LastValidSubscriptionEnd,
MAX(case when MinSub.Id!=S.ID then 1 else 0 end as IsPayingCustomer,
max(case when MonthlyPrice>0 then 0 end) as ActiveSubscriptionMonthlyPrice
FROM dbo.ClientSubscriptions S
join (
select ClientId, min(Id) as Id
from dbo.ClientSubscriptions
where IsDeleted=0
group by ClientId
) MinSub on MinSub.ClientId=ClientSubscriptions.ClientId
where IsDeleted=0 and (SubscriptionEnd is null or SubscriptionEnd>getdate())
group by ClientId
) Subscriptions on Subscriptions.ClientId=C.Id
left join (
select ClientId,
DiscountCouponCode,
row_number() over(partition by ClientId, order by Id) rn
from dbo.ClientPayments
) ClientPayments on ClientPayments.ClientId=C.ID and rn=1
left join dbo.DiscountCoupons on DiscountCoupons.Code=ClientPayments.DiscountCouponCode
left join (
select ClientId,
count(*) as TotalFilesCount,
sum(FileSize)/1048576.0 as TotalFilesSize
from dbo.ClientFiles
group by ClientId
) ClientFiles on ClientFiles.ClientId=Client.Id
left join (
SELECT Cust_id, COUNT(1) AS CrmCallCount
FROM dbo.Tipulog_Crm_Calls_new
group by Cust_id
) Crm_Calls on Crm_Calls.Cust_id=C.Id
WHERE C.IsDeleted = 0

Answer 2

This is a very partial answer, but you asked how to refer to a table once instead of multiple times in multiple subqueries.
This is an example of how you would replace all those subqueries to the Patients & Treatments tables, and also the cities table. You really need to learn about joins.
FROM dbo.Clients AS C
join dbo.Cities on Cities.ID=c.CityID
left join (
SELECT ClientId,
COUNT(*) AS TotalPatientCount,
sum(case when IsDeleted = 0 AND IsDisabled = 0 then 1 else 0 end) AS ActivePatientCount,
MAX(CreatedWhen) AS LastPatientAddition
FROM dbo.Patients
GROUP BY ClientId
) Patients on Patients.ClientId = C.Id
left join (
SELECT ClientId,
COUNT(*) AS TotalTreatmentCount,
MAX(CreatedWhen) AS LastTreatmentAddition
FROM dbo.Treatments
GROUP BY ClientId
) Treatments on Treatments.ClientID = C.Id
Then your column list replaces the subqueries to Patients and City like this:
Cities.Name AS City,
Patients.TotalPatientCount,
Patients.ActivePatientCount,
Patients.LastPatientAddition,
Treatments.TotalTreatmentCount,
Treatments.LastTreatmentAddition,
That should at least give you an idea.