FILE_ID (Transact-SQL)

file_name

Is an expression of type sysname that represents the name of the file for which to return the file ID.

smallint

file_name corresponds to the logical file name displayed in the name column in the sys.master_files or sys.database_files catalog views.

In SQL Server, the file identification number assigned to full-text catalogs is greater than 32767. Because the return type of the FILE_ID function is smallint, this function cannot be used for full-text files. Use FILE_IDEX instead.

The following example returns the file ID for the AdventureWorks_Data file.

USE AdventureWorks2012;
GO
SELECT FILE_ID('AdventureWorks2012_Data')AS 'File ID';
GO

Here is the result set.

File ID 
------- 
1
(1 row(s) affected)

Reference