How to define mdf,ldf files default location path in SQL script

Question

I want to give the script below to my client for installing a new database.
How can i rewrite this part of script to reflect their specific data and log file locations:

USE [master]
GO
/****** Object:  Database [PhoneBook]    Script Date: 2016/1/13 11:02:34 AM ******/
CREATE DATABASE [PhoneBook]
 CONTAINMENT = NONE
 ON  PRIMARY 
( NAME = N'PhoneBook', FILENAME = N'C:\Program Files (x86)\Microsoft SQL Server\MSSQL12.SQLEXPRESS\MSSQL\DATA\PhoneBook.mdf' , SIZE = 5120KB , MAXSIZE = UNLIMITED, FILEGROWTH = 1024KB )
 LOG ON 
( NAME = N'PhoneBook_log', FILENAME = N'C:\Program Files (x86)\Microsoft SQL Server\MSSQL12.SQLEXPRESS\MSSQL\DATA\PhoneBook_log.ldf' , SIZE = 2048KB , MAXSIZE = 2048GB , FILEGROWTH = 10%)
GO

My client's windows drive is not c.
Can i change these paths to reflect their sql installation path?
How can i tell this script find the right location?

Answer 1

USE [master]
GO

DECLARE @mdfPath NVARCHAR(max), @ldfPath NVARCHAR(max) , @SQL NVARCHAR(MAX), @instName NVARCHAR(max) = 'PhoneBook'


SELECT @mdfPath = SUBSTRING(physical_name, 1,CHARINDEX(N'master.mdf',LOWER(physical_name)) - 1)+@instName+N'.mdf'
       ,@ldfPath = SUBSTRING(physical_name, 1,CHARINDEX(N'master.mdf',LOWER(physical_name)) - 1)+@instName+N'.ldf'
FROM master.sys.master_files
WHERE database_id = 1 AND FILE_ID = 1


SELECT @SQL =
'CREATE DATABASE [PhoneBook]
 CONTAINMENT = NONE
 ON  PRIMARY 
( NAME = N'''+@instName+''', FILENAME = N'''+@mdfPath+''' , SIZE = 5120KB , MAXSIZE = UNLIMITED, FILEGROWTH = 1024KB )
 LOG ON 
( NAME = N'''+@instName+'_log'', FILENAME = N'''+@ldfPath+''' , SIZE = 2048KB , MAXSIZE = 2048GB , FILEGROWTH = 10%)'

PRINT(@SQL)
EXECUTE(@SQL)

GO