SQL Server Dynamic where clause query - sql

Question

I am trying to create a dynamic query I just to do with linq
from a in Customers
where (string.IsNullOrEmpty(name)? true : a.FirstName == name) && (string.IsNullOrEmpty(last)? true : a.LastName == last)
select a;
but now I need to do in on Stored Procedure and I don't want to concatenate for security reason and performance. The most close example I found is this query
declare #Name as varchar(100)
declare #GroupName as varchar(100)
set #Name = ''
set #GroupName = 'Manufacturing'
SELECT TOP (1000) [DepartmentID]
,[Name]
,[GroupName]
,[ModifiedDate]
FROM [AdventureWorks2017].[HumanResources].[Department]
where ([Name] = case
when #Name is null or #Name = '' then null
else #Name
end
)
and
(
[GroupName] = case
when #GroupName is null or #GroupName = '' then null
else #GroupName
end
)
This almost works. I think this should be the answer but the where clause fails for obvious reason.
I would like the where clause could produce '1=1' if the param "Name" or "GroupName" is null
example
#Name = "Somename"
#GroupName = null
where (Name = #Name) and (1 = 1)
--or
#Name = null
#GroupName = "Somegruopname"
where (1 = 1) and (GroupName = #GroupName)
--
#Name = null
#GroupName = null
where (1 = 1) and (1 = 1)

Answer 1

You want it to succeed if the variable is null or empty or a match, so I would just write that in your stored procedure.
WHERE (#FirstName is null OR #FirstName = '' OR [FirstName] = #FirstName)
AND (#LastName is null OR #LastName = '' OR [LastName] = #LastName)

Answer 2

Please try this:
declare #Name as varchar(100)
declare #GroupName as varchar(100) = 'Manufacturing'
set #Name = LTRIM(RTRIM(#Name))
set #GroupName = 'Manufacturing'
SELECT TOP (1000) [DepartmentID]
,[Name]
,[GroupName]
,[ModifiedDate]
FROM [AdventureWorks2017].[HumanResources].[Department]
where ([Name] = coalesce(#Name,'') = '' OR [Name] = #Name)
and
([GroupName] = coalesce(#GroupName, '') = '' OR [GroupName] = #GroupName)