--- title: "SQL Server 2016 Express LocalDB | Microsoft Docs" ms.custom: "" ms.date: "08/10/2016" ms.prod: "sql" ms.prod_service: "database-engine" ms.service: "" ms.component: "configure-windows" ms.reviewer: "" ms.suite: "sql" ms.technology: - "database-engine" ms.tgt_pltfrm: "" ms.topic: "article" helpviewer_keywords: - "user instances" - "LocalDB, described" - "local database runtime" - "file database" - "LocalDB" ms.assetid: 5a641a46-7cfb-4d7b-a90d-6e4625719d74 caps.latest.revision: 42 author: "MikeRayMSFT" ms.author: "mikeray" manager: "craigg" ms.workload: "Active" --- # SQL Server 2016 Express LocalDB [!INCLUDE[appliesto-ss-xxxx-xxxx-xxx-md](../../includes/appliesto-ss-xxxx-xxxx-xxx-md.md)] > For content related to previous versions of SQL Server, see [SQL Server 2014 Express LocalDB](https://msdn.microsoft.com/en-US/library/hh510202(SQL.120).aspx). Microsoft SQL Server 2016 Express **LocalDB** is a feature of [SQL Server Express](https://msdn.microsoft.com/library/ms144275(SQL.130).aspx) targeted to developers. It is available on SQL Server 2016 Express with Advanced Services. **LocalDB** installation copies a minimal set of files necessary to start the [!INCLUDE[ssDEnoversion](../../includes/ssdenoversion-md.md)]. Once LocalDB is installed, you can initiate a connection using a special connection string. When connecting, the necessary [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] infrastructure is automatically created and started, enabling the application to use the database without complex configuration tasks. Developer Tools can provide developers with a [!INCLUDE[ssDEnoversion](../../includes/ssdenoversion-md.md)] that lets them write and test [!INCLUDE[tsql](../../includes/tsql-md.md)] code without having to manage a full server instance of [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)]. ## Try it out! - To download and install SQL Server 2016 Express, go to **[SQL Server downloads](https://www.microsoft.com/en-us/sql-server/sql-server-downloads)**. LocalDB is a feature you select during installation, and is available when you download the media. If you download the media, either choose **Express Advanced** or the **LocalDB** package. - Have an Azure account? Then go **[here](https://azure.microsoft.com/en-us/services/virtual-machines/sql-server/)** to spin up a Virtual Machine with [!INCLUDE[ssSQL15](../../includes/sssql15-md.md)] already installed. ## Install LocalDB Install **LocalDB** through the installation wizard or by using the SqlLocalDB.msi program. **LocalDB** is an option when installing [!INCLUDE[ssExpCurrent](../../includes/ssexpcurrent-md.md)]. Select **LocalDB** on the **Feature Selection/Shared Features** page during installation. There can be only one installation of the **LocalDB** binary files for each major [!INCLUDE[ssDEnoversion](../../includes/ssdenoversion-md.md)] version. Multiple [!INCLUDE[ssDE](../../includes/ssde-md.md)] processes can be started and will all use the same binaries. An instance of the [!INCLUDE[ssDEnoversion](../../includes/ssdenoversion-md.md)] started as the **LocalDB** has the same limitations as [!INCLUDE[ssExpress](../../includes/ssexpress-md.md)]. An instance of [!INCLUDE[ssExpress](../../includes/ssexpress-md.md)] **LocalDB** is managed by using the **SqlLocalDB.exe** utility. [!INCLUDE[ssExpress](../../includes/ssexpress-md.md)] **LocalDB** should be used in place of the [!INCLUDE[ssExpress](../../includes/ssexpress-md.md)] user instance feature which is deprecated. ## Description The **LocalDB** setup program uses the SqlLocalDB.msi program to install the necessary files on the computer. Once installed, **LocalDB** is an instance of [!INCLUDE[ssExpress](../../includes/ssexpress-md.md)] that can create and open [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] databases. The system database files for the database are stored in the users' local AppData path which is normally hidden. For example **C:\Users\\\AppData\Local\Microsoft\Microsoft SQL Server Local DB\Instances\LocalDBApp1\\**. User database files are stored where the user designates, typically somewhere in the **C:\Users\\\Documents\\** folder. For more information about including **LocalDB** in an application, see the [!INCLUDE[vsprvs](../../includes/vsprvs-md.md)] documentation [Local Data Overview](http://msdn.microsoft.com/library/ms233817\(VS.110\).aspx), [Walkthrough: Creating a SQL Server LocalDB Database](http://msdn.microsoft.com/library/ms233763\(VS.110\).aspx), and [Walkthrough: Connecting to Data in a SQL Server LocalDB Database (Windows Forms)](http://msdn.microsoft.com/library/ms171890\(VS.110\).aspx). For more information about the **LocalDB** API, see [SQL Server Express LocalDB Instance API Reference](http://msdn.microsoft.com/library/hh234692\(SQL.110\).aspx) and [LocalDBStartInstance Function](http://msdn.microsoft.com/library/hh217143\(SQL.110\).aspx). The SqlLocalDb utility can create new instances of **LocalDB**, start and stop an instance of **LocalDB**, and includes options to help you manage **LocalDB**. For more information about the SqlLocalDb utility, see [SqlLocalDB Utility](../../tools/sqllocaldb-utility.md). The instance collation for **LocalDB** is set to SQL_Latin1_General_CP1_CI_AS and cannot be changed. Database-level, column-level, and expression-level collations are supported normally. Contained databases follow the metadata and tempdb collations rules defined by [Contained Database Collations](../../relational-databases/databases/contained-database-collations.md). ### Restrictions **LocalDB** cannot be a merge replication subscriber. **LocalDB** does not support FILESTREAM. **LocalDB** only allows local queues for Service Broker. An instance of **LocalDB** owned by the built-in accounts such as NT AUTHORITY\SYSTEM can have manageability issues due to windows file system redirection; Instead use a normal windows account as the owner. ### Automatic and Named Instances **LocalDB** supports two kinds of instances: Automatic instances and named instances. - Automatic instances of **LocalDB** are public. They are created and managed automatically for the user and can be used by any application. One automatic instance of **LocalDB** exists for every version of **LocalDB** installed on the user’s computer. Automatic instances of **LocalDB** provide seamless instance management. There is no need to create the instance; it just works. This allows for easy application installation and migration to a different computer. If the target machine has the specified version of **LocalDB** installed, the automatic instance of **LocalDB** for that version is available on the target machine as well. Automatic instances of **LocalDB** have a special pattern for the instance name that belongs to a reserved namespace. This prevents name conflicts with named instances of **LocalDB**. The name for the automatic instance is **MSSQLLocalDB**. - Named instances of **LocalDB** are private. They are owned by a single application that is responsible for creating and managing the instance. Named instances provide isolation from other instances and can improve performance by reducing resource contention with other database users. Named instances must be created explicitly by the user through the **LocalDB** management API or implicitly via the app.config file for a managed application (although managed application may also use the API, if desired). Each named instance of **LocalDB** has an associated **LocalDB** version that points to the respective set of **LocalDB** binaries. The instance name of a **LocalDB** is **sysname** data type and can have up to 128 characters. (This differs from regular named instances of [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)], which limits names to regular NetBIOS names of 16 ASCII chars.) The name of an instance of **LocalDB** can contain any Unicode characters that are legal within a filename. A named instance that uses an automatic instance name becomes an automatic instance. Different users of a computer can have instances with the same name. Each instance is a different processes running as a different user. ## Shared Instances of LocalDB To support scenarios where multiple users of the computer need to connect to a single instance of **LocalDB**, **LocalDB** supports instance sharing. An instance owner can choose to allow the other users on the computer to connect to his instance. Both automatic and named instances of **LocalDB** can be shared. To share an instance of **LocalDB** a user selects a shared name (alias) for it. Because the shared name is visible to all users of the computer, this shared name must be unique on the computer. The shared name for an instance of **LocalDB** has the same format as the named instance of **LocalDB**. Only an administrator on the computer can create a shared instance of **LocalDB**. A shared instance of **LocalDB** can be unshared by an administrator or by the owner of the shared instance of **LocalDB**. To share and unshared an instance of **LocalDB**, use the `LocalDBShareInstance` and `LocalDBUnShareInstance` methods of the **LocalDB** API, or the share and unshared options of the SqlLocalDb utility. ## Starting LocalDB and Connecting to LocalDB ### Connecting to the Automatic Instance The easiest way to use **LocalDB** is to connect to the automatic instance owned by the current user by using the connection string **"Server=(localdb)\MSSQLLocalDB;Integrated Security=true"**. To connect to a specific database by using the file name, connect using a connection string similar to **"Server=(LocalDB)\MSSQLLocalDB; Integrated Security=true ;AttachDbFileName=D:\Data\MyDB1.mdf"**. > [!NOTE] > The first time a user on a computer tries to connect to **LocalDB**, the automatic instance must be both created and started. The extra time for the instance to be created can cause the connection attempt to fail with a timeout message. When this happens, wait a few seconds to let the creation process complete, and then connect again. ### Creating and Connecting to a Named Instances In addition to the automatic instance, **LocalDB** also supports named instances. Use the SqlLocalDB.exe program to create, start, and stop an named instance of **LocalDB**. For more information about SqlLocalDB.exe, see [SqlLocalDB Utility](../../tools/sqllocaldb-utility.md). ```ms-dos REM Create an instance of LocalDB "C:\Program Files\Microsoft SQL Server\130\Tools\Binn\SqlLocalDB.exe" create LocalDBApp1 REM Start the instance of LocalDB "C:\Program Files\Microsoft SQL Server\130\Tools\Binn\SqlLocalDB.exe" start LocalDBApp1 REM Gather information about the instance of LocalDB "C:\Program Files\Microsoft SQL Server\130\Tools\Binn\SqlLocalDB.exe" info LocalDBApp1 ``` The last line above, returns information similar to the following. ||| |-|-| |Name|"LocalDBApp1"| |Version|\| |Shared name|""| |Owner|"\"| |Auto create|No| |State|running| |Last start time|\| |Instance pipe name|np:\\\\.\pipe\LOCALDB#F365A78E\tsql\query| > [!NOTE] > If your application uses a version of .NET before 4.0.2 you must connect directly to the named pipe of the **LocalDB**. The Instance pipe name value is the named pipe that the instance of **LocalDB** is listening on. The portion of the Instance pipe name after LOCALDB# will change each time the instance of **LocalDB** is started. To connect to the instance of **LocalDB** by using [!INCLUDE[ssManStudioFull](../../includes/ssmanstudiofull-md.md)], type the Instance pipe name in the **Server name** box of the **Connect to [!INCLUDE[ssDE](../../includes/ssde-md.md)]** dialog box. From your custom program you can establish connection to the instance of **LocalDB** using a connection string similar to `SqlConnection conn = new SqlConnection(@"Server=np:\\.\pipe\LOCALDB#F365A78E\tsql\query");` ### Connecting to a Shared Instance of LocalDB To connect to a shared instance of **LocalDB** add **.\\** (dot + backslash) to the connection string to reference the namespace reserved for shared instances. For example, to connect to a shared instance of **LocalDB** named `AppData` use a connection string such as `(localdb)\.\AppData` as part of the connection string. A user connecting to a shared instance of **LocalDB** that they do not own must have a Windows Authentication or [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Authentication login. ## Troubleshooting For information about troubleshooting **LocalDB**, see [Troubleshooting SQL Server 2012 Express LocalDB](http://social.technet.microsoft.com/wiki/contents/articles/4609.aspx). ## Permissions An instance of [!INCLUDE[ssExpCurrent](../../includes/ssexpcurrent-md.md)]**LocalDB** is an instance created by a user for their use. Any user on the computer can create a database using an instance of **LocalDB**, storing files under their user profile and running the process under their credentials. By default, access to the instance of **LocalDB** is limited to its owner. The data contained in the **LocalDB** is protected by file system access to the database files. If user database files are stored in a shared location, the database can be opened by anyone with file system access to that location by using an instance of **LocalDB** that they own. If the database files are in a protected location, such as the users data folder, only that user, and any administrators with access to that folder, can open the database. The **LocalDB** files can only be opened by one instance of **LocalDB** at a time. > [!NOTE] > **LocalDB** always runs under the users security context; that is, **LocalDB** never runs with credentials from the local Administrator’s group. This means that all database files used by a **LocalDB** instance must be accessible using the owning user’s Windows account, without considering membership in the local Administrators group. ## See Also [SqlLocalDB Utility](../../tools/sqllocaldb-utility.md)