attach.sql
IF DB_ID('MyDatabase') IS NULL
BEGIN
CREATE DATABASE MyDatabase ON
(FILENAME = 'E:\PortableSQL\Data\MyDatabase.mdf'),
(FILENAME = 'E:\PortableSQL\Data\MyDatabase_log.ldf')
FOR ATTACH;
END
start.bat
@echo off
echo Starting LocalDB...
SqlLocalDB start MSSQLLocalDB
echo Attaching database from USB drive...
SqlCmd -S (localdb)\MSSQLLocalDB -i "%~dp0attach.sql"
echo Ready. Connect using (localdb)\MSSQLLocalDB
pause
stop.bat
@echo off
echo Detaching database...
SqlCmd -S (localdb)\MSSQLLocalDB -Q "EXEC sp_detach_db 'MyDatabase'"
echo Stopping LocalDB...
SqlLocalDB stop MSSQLLocalDB
echo Safe to remove USB drive.
pause
Download SqlLocalDB.msi from Microsoft (search "SQL Server Express LocalDB"). Run it. No SQL Server Management Studio (SSMS) needed unless desired.
Verify installation by opening Command Prompt and typing: ms sql server express portable
SqlLocalDB info
You should see MSSQLLocalDB as the default instance.
Since there is no official "SQLServerPortable.exe" download, you have to use workarounds. Here are the three most common approaches:
From SQL Server 2005 to 2012, Microsoft supported User Instances (also called RANU – Run As Normal User). A non-admin user could attach an .mdf file directly from their user profile using a special connection string:
Server=.\SQLEXPRESS;AttachDbFilename=C:\MyData\MyDB.mdf;User Instance=true; attach
This behaved like a portable database for that specific user—but the SQL Server Windows service still had to be installed system-wide by an admin first. No admin, no user instances.
Ongoing Support: User Instances were deprecated after SQL Server 2012. Modern SQL Server Express (2014+) uses Contained Databases and AttachDbFileName without the "User Instance" flag, but again, the main service must be pre-installed.
| Need | Solution | | :--- | :--- | | Official Microsoft Environment | Use Docker containers or install LocalDB. | | MSSQL specifically on a USB stick | Use a PortableApps wrapper (requires Admin rights). | | Just need a database on a USB stick | Use SQLite. It is lightweight, standard, and truly zero-install. |
Recommendation: Unless you are specifically testing T-SQL syntax that is unique to Microsoft SQL Server, switch to SQLite for your portable database needs. It is robust, infinitely portable, and requires zero configuration. no admin rights) is impossible. However
Avoid them. Unofficial repacks often contain malware, violate Microsoft’s EULA, and are unsupported. Always download from Microsoft.
Connect to LocalDB using SqlCmd or SSMS:
SqlCmd -S (localdb)\MSSQLLocalDB
Then run:
CREATE DATABASE MyDatabase
ON (NAME = MyDatabase_dat, FILENAME = 'E:\PortableSQL\Data\MyDatabase.mdf')
LOG ON (NAME = MyDatabase_log, FILENAME = 'E:\PortableSQL\Data\MyDatabase_log.ldf');
GO
First, the most important takeaway: Microsoft does not offer an official "portable" version of SQL Server Express. SQL Server is a complex Windows service with deep registry integration, system databases, and dependencies on Windows APIs. A classic portable app (single .exe in a folder, no installation, no admin rights) is impossible.
However, there is a "portable" workaround using SQL Server Express LocalDB, and a legacy option called "User Instances" (deprecated). This review focuses on the viable approach.