SQL Server - View that contains a TOP 1 select column - sql-server

Question

I have a customer table, and then there's a separate transactional table that cross-references the customer table. With one particular column that I would like to present to the consumer as a combined SQL view. This transactional column is referred to as LastEdited.
The view itself is fine, if I run SELECT statements by querying columns like FirstName, LastName, etc. Where I run into issues is when querying the LastEdited column. This column is using a TOP 1 select criteria. For example, if I query LastEdited BETWEEN '1/1/2019 00:00:01' and '6/30/2019 23:59:59'. The results take a long time, since there are obvious performance penalties.
Any suggestions on how best to handle this? I've tried creating the column for this view by invoking a scalar function, like:
(select dbo.fncUser_LastCustomerEditDate(c.CustomerNo)) as LastEdited
This scalar function basically returns the TOP 1 record. I've also tried creating the column by referencing it against an OUTER APPLY, like:
...OUTER APPLY (SELECT top 1 GMTTimestamp from dbo.tbl121_DataLog dl where dl.PrimaryKey = c.Id and dl.DBActionId In (600001, 600002) order by dl.GMTTimeStamp DESC) dl
so that my SELECT list just looks at:
dl.GMTTimeStamp as LastEdited
Neither option provides me the ability to quickly return results by querying the resultant view based on this column.
Any help or suggestions would be appreciated!
Here are the two view constructions I've tried so far:
CREATE VIEW [dbo].[viwUser_Customers_Custom2]
AS
SELECT c.Id, c.Type, c.CustomerNo, sit.Code AS PrimarySiteCode, sit.Name AS PrimarySiteName, emp.Code AS PrimarySalespersonCode,
emp.Name AS PrimarySalespersonName, c.Title, c.FirstName, c.MiddleName, c.LastName, c.NickName, c.Greeting, c.PreviousName,
dbo.fncCustContactMethodText(c.PreferredContactMethod) AS PreferredContactMethod, cad.Address1, cad.Address2, cad.Address3, cad.City, cad.State,
cad.PostCode, cad.Country, cpp.CountryPrefix AS PhoneCountryPrefix, cpp.AreaCode AS PhoneAreaCode, cpp.Number AS PhoneNumber,
cpp.Extension AS PhoneExtension, dbo.fncCustFormattedPhoneNo(cpp.CountryPrefix, cpp.AreaCode, cpp.Number, cpp.Extension)
AS PhoneNumberFormatted, cpf.CountryPrefix AS FaxCountryPrefix, cpf.AreaCode AS FaxAreaCode, cpf.Number AS FaxNumber,
cpf.Extension AS FaxExtension, dbo.fncCustFormattedPhoneNo(cpf.CountryPrefix, cpf.AreaCode, cpf.Number, cpf.Extension) AS FaxNumberFormatted,
cpm.CountryPrefix AS MobileCountryPrefix, cpm.AreaCode AS MobileAreaCode, cpm.Number AS MobileNumber, cpm.Extension AS MobileExtension,
dbo.fncCustFormattedPhoneNo(cpm.CountryPrefix, cpm.AreaCode, cpm.Number, cpm.Extension) AS MobileNumberFormatted, cpe.EmailAddress, c.Sex,
c.UDFList1, c.UDFList2, c.UDFList3, c.UDFList4, c.UDFList5, c.UDFList6, c.UDFList7, c.UDFList8, c.UDFList9, c.UDFList10, c.UDFList11, c.UDFList12,
c.FingerSize1 AS LeftLittleFingerSize, c.FingerSize2 AS LeftRingFingerSize, c.FingerSize3 AS LeftMiddleFingerSize,
c.FingerSize4 AS LeftIndexFingerSize, c.FingerSize5 AS LeftThumbSize, c.FingerSize6 AS RightThumbSize, c.FingerSize7 AS RightIndexFingerSize,
c.FingerSize8 AS RightMiddleFingerSize, c.FingerSize9 AS RightRingFingerSize, c.FingerSize10 AS RightLittleFingerSize, c.LeftWristSize,
c.RightWristSize, c.NeckSize, c.SocSecNumber, c.POSComments, c.SecureComments, c.Status, c.Active, c.Day, c.Month, c.Year, dbo.fncGetDOB(c.Day,
c.Month, c.Year) AS BirthDate, dbo.fncGetAge(c.Day, c.Month, c.Year, c.Age, c.AgeReferenceDate, GETDATE()) AS Age, CAST('' AS varchar(1000))
AS MailingName, CAST('' AS varchar(1000)) AS GreetingName, CAST(0 AS money) AS CustomerSalesTotalForDateRange, CAST(0 AS money)
AS CustomerSalesTotal, CAST('' AS varchar(50)) AS PartnerCustomerNo, CAST('' AS varchar(20)) AS PartnerBirthDate, CAST(0 AS money)
AS PartnerSalesTotalForDateRange, CAST(0 AS money) AS PartnerSalesTotal, dbo.fnc604S_GetAnniversary(c.Id) as Anniversary,
Coalesce((Select Top 1 cd.DiscountPercent From tbl605_CustDiscount cd Where cd.CustomerId = c.Id),0) as DiscountPercent,
dl.GMTTimeStamp as LastEdited
FROM dbo.tbl600_Customer AS c INNER JOIN
dbo.tbl103_Sites AS sit ON c.SiteId = sit.Id LEFT OUTER JOIN
dbo.tbl601_CustAddress AS cad ON cad.CustomerId = c.Id AND cad.[Default] = 1 LEFT OUTER JOIN
dbo.tbl602_CustPhone AS cpp ON cpp.CustomerId = c.Id AND cpp.Device = 1 AND cpp.DeviceDefault = 1 LEFT OUTER JOIN
dbo.tbl602_CustPhone AS cpf ON cpf.CustomerId = c.Id AND cpf.Device = 3 AND cpf.DeviceDefault = 1 LEFT OUTER JOIN
dbo.tbl602_CustPhone AS cpm ON cpm.CustomerId = c.Id AND cpm.Device = 2 AND cpm.DeviceDefault = 1 LEFT OUTER JOIN
dbo.tbl602_CustPhone AS cpe ON cpe.CustomerId = c.Id AND cpe.Device = 4 AND cpe.DeviceDefault = 1 LEFT OUTER JOIN
dbo.tbl405_Employees AS emp ON dbo.fnc600S_GetPrimarySalespersonId(c.Id) = emp.Id OUTER APPLY
(SELECT top 1 GMTTimestamp from dbo.tbl121_DataLog dl where dl.PrimaryKey = c.Id and dl.DBActionId In (600001, 600002) order by dl.GMTTimeStamp DESC) dl
GO
CREATE VIEW [dbo].[viwUser_Customers_Custom]
AS
SELECT c.Id, c.Type, c.CustomerNo, sit.Code AS PrimarySiteCode, sit.Name AS PrimarySiteName, emp.Code AS PrimarySalespersonCode,
emp.Name AS PrimarySalespersonName, c.Title, c.FirstName, c.MiddleName, c.LastName, c.NickName, c.Greeting, c.PreviousName,
dbo.fncCustContactMethodText(c.PreferredContactMethod) AS PreferredContactMethod, cad.Address1, cad.Address2, cad.Address3, cad.City, cad.State,
cad.PostCode, cad.Country, cpp.CountryPrefix AS PhoneCountryPrefix, cpp.AreaCode AS PhoneAreaCode, cpp.Number AS PhoneNumber,
cpp.Extension AS PhoneExtension, dbo.fncCustFormattedPhoneNo(cpp.CountryPrefix, cpp.AreaCode, cpp.Number, cpp.Extension)
AS PhoneNumberFormatted, cpf.CountryPrefix AS FaxCountryPrefix, cpf.AreaCode AS FaxAreaCode, cpf.Number AS FaxNumber,
cpf.Extension AS FaxExtension, dbo.fncCustFormattedPhoneNo(cpf.CountryPrefix, cpf.AreaCode, cpf.Number, cpf.Extension) AS FaxNumberFormatted,
cpm.CountryPrefix AS MobileCountryPrefix, cpm.AreaCode AS MobileAreaCode, cpm.Number AS MobileNumber, cpm.Extension AS MobileExtension,
dbo.fncCustFormattedPhoneNo(cpm.CountryPrefix, cpm.AreaCode, cpm.Number, cpm.Extension) AS MobileNumberFormatted, cpe.EmailAddress, c.Sex,
c.UDFList1, c.UDFList2, c.UDFList3, c.UDFList4, c.UDFList5, c.UDFList6, c.UDFList7, c.UDFList8, c.UDFList9, c.UDFList10, c.UDFList11, c.UDFList12,
c.FingerSize1 AS LeftLittleFingerSize, c.FingerSize2 AS LeftRingFingerSize, c.FingerSize3 AS LeftMiddleFingerSize,
c.FingerSize4 AS LeftIndexFingerSize, c.FingerSize5 AS LeftThumbSize, c.FingerSize6 AS RightThumbSize, c.FingerSize7 AS RightIndexFingerSize,
c.FingerSize8 AS RightMiddleFingerSize, c.FingerSize9 AS RightRingFingerSize, c.FingerSize10 AS RightLittleFingerSize, c.LeftWristSize,
c.RightWristSize, c.NeckSize, c.SocSecNumber, c.POSComments, c.SecureComments, c.Status, c.Active, c.Day, c.Month, c.Year, dbo.fncGetDOB(c.Day,
c.Month, c.Year) AS BirthDate, dbo.fncGetAge(c.Day, c.Month, c.Year, c.Age, c.AgeReferenceDate, GETDATE()) AS Age, CAST('' AS varchar(1000))
AS MailingName, CAST('' AS varchar(1000)) AS GreetingName, CAST(0 AS money) AS CustomerSalesTotalForDateRange, CAST(0 AS money)
AS CustomerSalesTotal, CAST('' AS varchar(50)) AS PartnerCustomerNo, CAST('' AS varchar(20)) AS PartnerBirthDate, CAST(0 AS money)
AS PartnerSalesTotalForDateRange, CAST(0 AS money) AS PartnerSalesTotal, dbo.fnc604S_GetAnniversary(c.Id) as Anniversary,
Coalesce((Select Top 1 cd.DiscountPercent From tbl605_CustDiscount cd Where cd.CustomerId = c.Id),0) as DiscountPercent, (select dbo.fncUser_LastCustomerEditDate(c.CustomerNo)) as LastEdited
FROM dbo.tbl600_Customer AS c INNER JOIN
dbo.tbl103_Sites AS sit ON c.SiteId = sit.Id LEFT OUTER JOIN
dbo.tbl601_CustAddress AS cad ON cad.CustomerId = c.Id AND cad.[Default] = 1 LEFT OUTER JOIN
dbo.tbl602_CustPhone AS cpp ON cpp.CustomerId = c.Id AND cpp.Device = 1 AND cpp.DeviceDefault = 1 LEFT OUTER JOIN
dbo.tbl602_CustPhone AS cpf ON cpf.CustomerId = c.Id AND cpf.Device = 3 AND cpf.DeviceDefault = 1 LEFT OUTER JOIN
dbo.tbl602_CustPhone AS cpm ON cpm.CustomerId = c.Id AND cpm.Device = 2 AND cpm.DeviceDefault = 1 LEFT OUTER JOIN
dbo.tbl602_CustPhone AS cpe ON cpe.CustomerId = c.Id AND cpe.Device = 4 AND cpe.DeviceDefault = 1 LEFT OUTER JOIN
dbo.tbl405_Employees AS emp ON dbo.fnc600S_GetPrimarySalespersonId(c.Id) = emp.Id
GO
Time lags of 1-2 minutes querying the SQL view.

Answer 1

I found an easier way to accomplish this. Will just add a SQL trigger to insert a timestamped row into a supplementary table. This table will have the proper construction to make for quicker lookups.