It depends on whether default path is set for data and log files or not.

If the path is set explicitly at Properties => Database Settings => Database default locations then SQL server stores it at SoftwareMicrosoftMSSQLServerMSSQLServer in DefaultData and DefaultLog values.

However, if these parameters aren t set explicitly, SQL server uses Data and Log paths of master database.

Bellow is the script that covers both cases. This is simplified version of the query that SQL Management Studio runs.

Also, note that I use xp_instance_regread instead of xp_regread, so this script will work for any instance, default or named.

declare @DefaultData nvarchar(512)
exec master.dbo.xp_instance_regread N HKEY_LOCAL_MACHINE , N SoftwareMicrosoftMSSQLServerMSSQLServer , N DefaultData , @DefaultData output

declare @DefaultLog nvarchar(512)
exec master.dbo.xp_instance_regread N HKEY_LOCAL_MACHINE , N SoftwareMicrosoftMSSQLServerMSSQLServer , N DefaultLog , @DefaultLog output

declare @DefaultBackup nvarchar(512)
exec master.dbo.xp_instance_regread N HKEY_LOCAL_MACHINE , N SoftwareMicrosoftMSSQLServerMSSQLServer , N BackupDirectory , @DefaultBackup output

declare @MasterData nvarchar(512)
exec master.dbo.xp_instance_regread N HKEY_LOCAL_MACHINE , N SoftwareMicrosoftMSSQLServerMSSQLServerParameters , N SqlArg0 , @MasterData output
select @MasterData=substring(@MasterData, 3, 255)
select @MasterData=substring(@MasterData, 1, len(@MasterData) - charindex(  , reverse(@MasterData)))

declare @MasterLog nvarchar(512)
exec master.dbo.xp_instance_regread N HKEY_LOCAL_MACHINE , N SoftwareMicrosoftMSSQLServerMSSQLServerParameters , N SqlArg2 , @MasterLog output
select @MasterLog=substring(@MasterLog, 3, 255)
select @MasterLog=substring(@MasterLog, 1, len(@MasterLog) - charindex(  , reverse(@MasterLog)))

select 
    isnull(@DefaultData, @MasterData) DefaultData, 
    isnull(@DefaultLog, @MasterLog) DefaultLog,
    isnull(@DefaultBackup, @MasterLog) DefaultBackup

You can achieve the same result by using SMO. Bellow is C# sample, but you can use any other .NET language or PowerShell.

using (var connection = new SqlConnection("Data Source=.;Integrated Security=SSPI"))
{
    var serverConnection = new ServerConnection(connection);
    var server = new Server(serverConnection);
    var defaultDataPath = string.IsNullOrEmpty(server.Settings.DefaultFile) ? server.MasterDBPath : server.Settings.DefaultFile;
    var defaultLogPath = string.IsNullOrEmpty(server.Settings.DefaultLog) ? server.MasterDBLogPath : server.Settings.DefaultLog;
}

It is so much simpler in SQL Server 2012 and above, assuming you have default paths set (which is probably always a right thing to do):

select 
    InstanceDefaultDataPath = serverproperty( InstanceDefaultDataPath ),
    InstanceDefaultLogPath = serverproperty( InstanceDefaultLogPath )

Even though this is a very old thread, I feel like I need to contribute a simple solution. Any time that you know where in Management Studio a parameter is located that you want to access for any sort of automated script, the easiest way is to run a quick profiler trace on a standalone test system and capture what Management Studio is doing on the backend.

In this instance, assuming you are interested in finding the default data and log locations you can do the following:

SELECT
  SERVERPROPERTY( instancedefaultdatapath ) AS [DefaultFile],
  SERVERPROPERTY( instancedefaultlogpath ) AS [DefaultLog]

I stumbled across this solution in the documentation for the Create Database statement in the help for SQL Server:

SELECT SUBSTRING(physical_name, 1, CHARINDEX(N master.mdf , LOWER(physical_name)) - 1)
                  FROM master.sys.master_files
                  WHERE database_id = 1 AND file_id = 1

For the current database you can just use:

select physical_name fromsys.database_files;

to specify another database e.g. Model , use sys.master_files

select physical_name from sys.master_files where database_id = DB_ID(N Model );

As of Sql Server 2012, you can use the following query:

SELECT SERVERPROPERTY( INSTANCEDEFAULTDATAPATH ) as [Default_data_path], SERVERPROPERTY( INSTANCEDEFAULTLOGPATH ) as [Default_log_path];

(This was taken from a comment at http://technet.microsoft.com/en-us/library/ms174396.aspx, and tested.)

Various components of SQL Server (Data, Logs, SSAS, SSIS, etc) have a default directory. The setting for this can be found in the registry. Read more here:

http://technet.microsoft.com/en-us/library/ms143547%28SQL.90%29.aspx

So if you created a database using just CREATE DATABASE MyDatabaseName it would be created at the path specified in one of the settings above.

Now, if the admin / installer changed the default path, then the default path for the instance is stored in the registry at

HKEY_LOCAL_MACHINESOFTWAREMicrosoftMicrosoft SQL Server[INSTANCENAME]Setup

If you know the name of the instance then you can query the registry. This example is SQL 2008 specific - let me know if you need the SQL2005 path as well.

DECLARE @regvalue varchar(100)

EXEC master.dbo.xp_regread @rootkey= HKEY_LOCAL_MACHINE ,
        @key= SOFTWAREMicrosoftMicrosoft SQL ServerMSSQL10.MSSQLServerSetup ,
        @value_name= SQLDataRoot ,
        @value=@regvalue OUTPUT,
        @output =  no_output 

SELECT @regvalue as DataAndLogFilePath

Each database can be created overriding the server setting in a it s own location when you issue the CREATE DATABASE DBName statement with the appropriate parameters. You can find that out by executing sp_helpdb

exec sp_helpdb  DBName 

Keeping it simple:

use master
select DB.name, F.physical_name from sys.databases DB join sys.master_files F on DB.database_id=F.database_id

this will return all databases with associated files

From the GUI: open your server properties, go to Database Settings, and see Database default locations.

Note that you can drop your database files wherever you like, though it seems cleaner to keep them in the default directory.

Small nitpick: there is no data folder, only a default data folder.

Anyway, to find it, assuming you want to install for the first default instance:

HKEY_LOCAL_MACHINESOFTWAREMicrosoftMicrosoft SQL ServerMSSQL.1SetupSQLDataRoot

If there s a named instance, MSSQL.1 becomes something like MSSQL10.INSTANCENAME.

You can find default Data and Log locations for the current SQL Server instance by using the following T-SQL:

DECLARE @defaultDataLocation nvarchar(4000)
DECLARE @defaultLogLocation nvarchar(4000)

EXEC master.dbo.xp_instance_regread
    N HKEY_LOCAL_MACHINE ,
    N SoftwareMicrosoftMSSQLServerMSSQLServer ,
    N DefaultData , 
    @defaultDataLocation OUTPUT

EXEC master.dbo.xp_instance_regread
    N HKEY_LOCAL_MACHINE ,
    N SoftwareMicrosoftMSSQLServerMSSQLServer ,
    N DefaultLog , 
    @defaultLogLocation OUTPUT

SELECT @defaultDataLocation AS  Default Data Location ,
       @defaultLogLocation AS  Default Log Location 

Expanding on "splattered bits" answer, here is a complete script that does it:

@ECHO off
SETLOCAL ENABLEDELAYEDEXPANSION

SET _baseDirQuery=SELECT SUBSTRING(physical_name, 1, CHARINDEX(N master.mdf , LOWER(physical_name)) - 1) ^
 FROM master.sys.master_files WHERE database_id = 1 AND file_id = 1;
ECHO.
SQLCMD.EXE -b -E -S localhost -d master -Q "%_baseDirQuery%" -W >data_dir.tmp
IF ERRORLEVEL 1 ECHO Error with automatically determining SQL data directory by querying your server&ECHO using Windows authentication.
CALL :getBaseDir data_dir.tmp _baseDir

IF "%_baseDir:~-1%"=="" SET "_baseDir=%_baseDir:~0,-1%"
DEL /Q data_dir.tmp
echo DataDir: %_baseDir%

GOTO :END
::---------------------------------------------
:: Functions 
::---------------------------------------------

:simplePrompt 1-question 2-Return-var 3-default-Val
SET input=%~3
IF "%~3" NEQ "" (
  :askAgain
  SET /p "input=%~1 [%~3]:"
  IF "!input!" EQU "" (
    GOTO :askAgain
  ) 
) else (
  SET /p "input=%~1 [null]: "
)   
SET "%~2=%input%"
EXIT /B 0

:getBaseDir fileName var
FOR /F "tokens=*" %%i IN (%~1) DO (
  SET "_line=%%i"
  IF "!_line:~0,2!" == "c:" (
    SET "_baseDir=!_line!"
    EXIT /B 0
  )
)
EXIT /B 1

:END
PAUSE

i would have done a backup restore simply becuase its easier and support versioning. Reference data especially needs to be versioned in order to know when it started taking effect. A dettach attach wont give you that ability. Also with backups you can continue to provide updated copies without having to shut down the database.

Alex s answer is the right one, but for posterity here s another option: create a new empty database. If you use CREATE DATABASE without specifying a target dir you get... the default data / log directories. Easy.

Personally however I d probably either:

• RESTORE the database to the developer s PC, rather than copy/attach (backups can be compressed, exposed on a UNC), or
• Use a linked server to avoid doing this in the first place (depends how much data goes over the join)

ps: 20gb is not huge, even in 2015. But it s all relative.

SELECT DISTINCT dbo.GetDirectoryPath(filename) AS InstanceDataPaths
FROM sys.sysaltfiles WHERE filename like  %.mdf  and filename not like  %MSSQLBinn\% 

SELECT DISTINCT dbo.GetDirectoryPath(filename) AS InstanceLogPaths
FROM sys.sysaltfiles WHERE filename like  %.ldf  and filename not like  %MSSQLBinn\% 

You can download detail SQL script from how to find the data directory for a SQL Server instance

You will get default location if user database by this query:

declare @DataFileName nVarchar(500)

declare @LogFileName   nVarchar(500)


set @DataFileName = (select top 1 RTRIM(LTRIM(name)) FROM master.sys.master_files where database_id >4 AND file_id = 1)+ .mdf 
set @LogFileName =   (select top 1 RTRIM(LTRIM(name)) FROM master.sys.master_files where database_id >4 AND file_id = 2)+ .ldf 

select  
( SELECT top 1 SUBSTRING(physical_name, 1, CHARINDEX(@DataFileName, LOWER(physical_name)) - 1) 
FROM master.sys.master_files
WHERE database_id >4 AND file_id = 1) as  Data File 
,

(SELECT top 1 SUBSTRING(physical_name, 1, CHARINDEX(@LogFileName, LOWER(physical_name)) - 1)
FROM master.sys.master_files
WHERE database_id >4 AND file_id = 2)  as  Log File