SSRS. Extra space between FirstName and LastName - reporting-services

Question

I have report that displays name (FirstName MiddleName LastName). Each field has a space between and works great when name has MiddleName. However, when MiddleName is NULL, space renders between FirstName and LastName. What is the best way to solve that problem?
I tried something like that:
=Fields!FirstName.Value & "" & iif (isNothing(Fields!MiddleName.Value), "", Fields!MiddleName.Value) & "" & Fields!LastName.Value

Answer 1

With your current expression there should be no spaces. If there are any spaces currently they must exist in your database... This can be confirmed by using TRIM on FirstName, MiddleName, LastName.
To properly format your string you need to use spaces between the "", and ensure the space following the middle name is contained within the iif statement
=TRIM(Fields!FirstName.Value) & " " &
iif (isNothing(TRIM(Fields!MiddleName.Value)),
"",
TRIM(Fields!MiddleName.Value) & " ")
& TRIM(Fields!LastName.Value)

Answer 2

Firstly your expression above doesn't returns a name with space.
I think you mean something like this with space:
=Fields!FirstName.Value & " " & iif (isNothing(Fields!MiddleName.Value), " ", Fields!MiddleName.Value) & " " & Fields!LastName.Value
Aside from Jonnus answer you could also use 'Len' to check its length.
If you only worry about the MiddleName you could use this expression using Len
=Fields!FirstName.Value & " " & IIF(Len(Fields!MiddleName.Value) < 1,"", Fields!MiddleName.Value) & " " & Fields!LastName.Value
But if I were you I would rather use sql function to handle this rather than do it in expression which is messy. And I could also reuse this for other reports than repeat the expression again.
Here is an example of function that returns a fullname with middle name of your format.
IF EXISTS (
SELECT *
FROM dbo.sysobjects
WHERE ID = OBJECT_ID(N'[dbo].[GetClientFullNameWithMiddleName]') AND
xtype in (N'FN', N'IF', N'TF'))
DROP FUNCTION [dbo].[GetClientFullNameWithMiddleName]
GO
CREATE FUNCTION [dbo].[GetClientFullNameWithMiddleName](#ClientID UNIQUEIDENTIFIER)
RETURNS NVARCHAR(MAX)
AS
BEGIN
DECLARE #FULLNAME NVARCHAR(MAX)
DECLARE #LASTNAME NVARCHAR(MAX)
DECLARE #FIRSTNAME NVARCHAR(MAX)
DECLARE #MIDDLENAME NVARCHAR(MAX)
SET #LASTNAME = ISNULL((SELECT Lastname FROM Client WHERE ClientID = #ClientID),'')
SET #FIRSTNAME = ISNULL((SELECT Firstname FROM Client WHERE ClientID = #ClientID),'')
SET #MIDDLENAME = ISNULL((SELECT Middlename FROM Client WHERE ClientID = #ClientID),'')
IF(#ClientID <> '00000000-0000-0000-0000-000000000000')
BEGIN
IF(#FIRSTNAME <> '')
BEGIN
SET #FULLNAME = CAST((#FIRSTNAME) AS NVARCHAR(MAX))
IF(#MIDDLENAME <> '' AND #FULLNAME <> '')
BEGIN
SET #FULLNAME = CAST((#FULLNAME + ' ' + #MIDDLENAME) AS NVARCHAR(MAX))
END
IF(#LASTNAME <> '' AND #FULLNAME <> '')
BEGIN
SET #FULLNAME = CAST((#FULLNAME + ' ' + #LASTNAME) AS NVARCHAR(MAX))
END
END
ELSE
BEGIN
SET #FULLNAME = CAST((#FIRSTNAME)AS NVARCHAR(MAX))
END
END
ELSE
BEGIN
SET #FULLNAME = ''
END
RETURN #FULLNAME
END
GO
Then you could use it like this
SELECT
[dbo].[GetClientFullNameWithMiddleInitial](ClientID)
FROM Client