This would be useful for creating databases using SQL scripts. The SQL query below returns the installation path of the DATA folder for the installed SQL Server.
SQL Script
1: DECLARE @device_directory NVARCHAR(520)
2: SELECT @device_directory = SUBSTRING(filename, 1, CHARINDEX(N'master.mdf', LOWER(filename)) - 1)
3: FROM master.dbo.sysaltfiles WHERE dbid = 1 AND fileid = 1
4:
5: print @device_directory
Output
C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL\DATA\