Passing a file path as a variable in SQL Server - sql-server

Question

I'm trying to add a file to a file group in order to create a partition in SQL Server. When I pass in a hardcoded file path to the the filename, the code works. But when I use a variable for the file path, I get an error
Incorrect syntax near #FilePath or Unexpected symbol #FilePath
This is my code:
USE StudentRepository
BEGIN
SET NOCOUNT ON;
DECLARE #FilePath NVARCHAR(MAX) = "C:\Program Files\Microsoft SQL Server\MSSQL14.MSSQLEXPRESS\MSSQL\DATA\",
#FileName NVARCHAR(MAX) = "FirstTerm2020",
#FileExt NVARCHAR(MAX) = ".NDF";
DECLARE #count INT = 0;
ALTER DATABASE StudentRepository
ADD FILE
(
NAME = 'FirstTerm2020',
FILENAME = #FilePath + #FileName + #FileExt, --Error here!
SIZE = 5MB,
MAXSIZE = 100MB,
FILEGROWTH = 5MB
)
TO FILEGROUP FirstTerm2020
END
When I pass a hardcoded file path to the filename, it works and creates the required partitions. as below
--Code omitted for brevity
FILENAME = "C:\Program Files\Microsoft SQL Server\MSSQL14.MSSQLEXPRESS\MSSQL\DATA\FirstTerm2020.NDF" --No error!
Please I need some help. How do I pass a file path as a variable?

Answer 1

This is how I solved the problem. I create a dynamic sql and passed the filepath variable like this.
USE StudentRepository
BEGIN
SET NOCOUNT ON;
DECLARE #FilePath NVARCHAR(MAX) = 'C:\Program Files\Microsoft SQL Server\MSSQL14.MSSQLEXPRESS\MSSQL\DATA\',
#FileName NVARCHAR(MAX) = 'SecondTerm2022',
#FileExt NVARCHAR(MAX) = '.NDF';
DECLARE #count INT = 0;
DECLARE #sql NVARCHAR(MAX) = '
ALTER DATABASE StudentRepository ADD FILEGROUP ' + #FileName + ';
ALTER DATABASE StudentRepository
ADD FILE
(
NAME = '+ #FileName + ',
FILENAME = ''' + #FilePath + #FileName + #FileExt + ''',
SIZE = 5MB,
MAXSIZE = 100MB,
FILEGROWTH = 5MB
)
TO FILEGROUP '+ #FileName
END
EXEC sp_executesql #sql
My major problem was that I was ommitting the three single quotes near #FilePath