Undocumented SQL Server 2012 Express LocalDB

As a developer of Microsoft Visual Studio, SQL Server 2012 Express LocalDB probably has gotten onto your machine without your notice. I will document some of my exploration on LocalDB in this post.

Installation and Location

There are three ways to get LocalDB onto your machines:

  1. Install together when installing Microsoft Visual Studio 2013 (this is my case);
  2. Install by using SqlLocalDB.msi found in SQL Server 2012 Express
  3. Install by downloading from Microsoft Download Centre directly (here).

The installation location is default to C:\Program Files\Microsoft SQL Server\110\LocalDB\Binn where sqlserv.exe is the main application.

The tools (utilities) to operate the LocalDB are SqlLocalDB, SQLCMD and bcp which are located at C:\Program Files\Microsoft SQL Server\110\Tools\Binn. Make sure to include it into your PATH.

SqlLocalDB

This is the utility to administrate the localdb instances.

  • to get help: sqllocaldb -?
  • to print the version: sqllocaldb versions
  • to create an instance: sqllocaldb create “YourInstanceName”
  • to delete an instance: sqllocaldb delete “YourInstanceName”
  • to start an instance: sqllocaldb start “YourInstanceName”
  • to stop an instance: sqllocaldb stop “YourInstanceName”
  • to share an instance: sqllocaldb share “YourInstanceName”
  • to unshared an instance: sqllocadbl unshare “YourInstanceName”
  • to list all your instances: sqllocaldb info
  • to list the status of an instance: sqllocaldb info “YourInstanceName”
  • to set the trace on and off: sqllocaldb trace on|off

If you’ve used VS 2013 to connect to LocalDB, VS 2013 would have created an instance for you (in my case is v11.0).

Even your instance is stopped, it will be auto-started when you try to connect to it first time either via VS 2013 or SQLCMD.

SQLCMD, BCP, process ‘sqlservr’

Both SQLCMD and BCP are well documented. The only difference between LocalDB and SQL server is that we need to put a bracket ‘()’ to indicate it is a LocalDB instead of hostname for the named instance┬álike:

sqlcmd -S ‘(LocalDB)\v11.0’

This is also applied to SSMS and VS 2013 connections. There is only one process “sqlservr” related to LocalDB. It is very lightweighted by using about 12MB RAM on my machine.

Some Examples

The following is executed in powershell:

Windows PowerShell
Copyright (C) 2013 Microsoft Corporation. All rights reserved.

PS C:\Users\henry> sqllocaldb info
Projects
v11.0
PS C:\Users\henry> sqllocaldb info "v11.0"
Name:               v11.0
Version:            11.0.3000.0
Shared name:
Owner:              PolarBear\henry
Auto-create:        Yes
State:              Stopped
Last start time:    12/31/2013 2:37:39 PM
Instance pipe name:
PS C:\Users\henry> sqllocaldb start "v11.0"
LocalDB instance "v11.0" started.
PS C:\Users\henry>  ps | where-object {$_.ProcessName -match 'sqlservr'}

Handles  NPM(K)    PM(K)      WS(K) VM(M)   CPU(s)     Id ProcessName
-------  ------    -----      ----- -----   ------     -- -----------
    492      20    67780      17140   311     3.83   2248 sqlservr


PS C:\Users\henry> sqllocaldb stop "v11.0"
LocalDB instance "v11.0" stopped.
PS C:\Users\henry> sqlcmd -S "(LocalDB)\v11.0"
1> use test
2> go
Changed database context to 'test'.
1> select count(*) from HR.Employees
2> go

-----------
          9

(1 rows affected)
1> shutdown
2> go
Server shut down by request from login PolarBear\henry.
1> exit
PS C:\Users\henry>

Sharing or Not

From A TechNet Article
When sharing a SqlLocalDB instance with a non-owner, you must re-start the instance for the other users to be able to see the instance you have shared. A non-owner cannot start an instance, so if you are going to share an instance with other users who can access your machine, you also need to be sure it has been started. When you create an instance you can do this as follows:

sqllocaldb create “MyInstance”
sqllocaldb share “MyInstance” “OurInstance”
sqllocaldb start “MyInstance”

You should add users explicitly when connected to the instance as the owner, e.g.

CREATE LOGIN [Domain\User] FROM WINDOWS;
GRANT CONNECT TO [Domain\User];
— other permissions…

In general, though, the purpose of SqlLocalDB is to serve as a sandbox for an individual developer on a machine, not to serve as a development environment for multiple users. Each user should be able to create, start, administer and use his/her own LocalDB instances.

Working With Model in Entity Framework

In the previous post, I showed how to reversed-engineer an entity framework model from a Microsoft SQL Server 2012 database, and query the model in a C# console program. In the following, I will expand it further on how to work on the model generated to perform the standard CRUD (Create, Read, Update, Delete) operations.

Model

The model generated in the last post was in a file (testContext.cs) where the database context (testContext) was derived from DbContext, in which the property Employees was exposed as an entity (DbSet). In the simple RDBMS terms, the physical database (test) is mapped to DbContext (testContext) while a physical table (employees) was mapped to an entity DbSet (Employees). The entity model is like a conceptual model in the database design process.

Little notes on database design process
In a normal database design process, we design a conceptual model first by using designer like Visual Studio EF Designer or Oracle SQL developer/modeler, which will produce an ER-Diagram (Entity-Relationship Diagram) as a result. From the model, we can generate the physical model which is a set of DDLs, to run on a specific RDBMS like Oracle, MS SQL Server, etc. and produce a database.

In our previous example, we reversed the design process from bottom up, and generated the conceptual model into Entity Framework in Visual Studio from the physical database structures in Microsoft SQL Server (Database: test; Table: HR.Employees). This process is called reversed engineering.

namespace EmployeeConsole.Models
{
    public partial class testContext : DbContext
    {
        ......
        public DbSet<Employee> Employees { get; set; }
        ......
    }
}

Work on Model

To work on the model, the first is to include your model, then instantiate a dbContext so that the CRUD ops can be performed within the instance lifetime.

Here is the code snippets. Refer to last post for details.

using EmployeeConsole.Models;
...
      using (var db = new testContext())
          {
             // TODO YOUR CRUD Ops
          }

How to Read (Find) a Record

            using (var db = new testContext())
            {

                var myemp = db.Employees.Find(3);
                Console.WriteLine("Locate and Display empid=3");
                Console.WriteLine("EmpID\t{0}",myemp.empid);
                Console.WriteLine("FName\t{0}", myemp.firstname);
                Console.WriteLine("LName\t{0}", myemp.lastname);
                Console.WriteLine("HDate\t{0}", myemp.hiredate);
                Console.WriteLine("Phone\t{0}", myemp.phone);
                Console.WriteLine("Country\t{0}", myemp.country);
                Console.WriteLine("Press any key to exit...");
                Console.ReadKey();
            }

How to Update a Record

            using (var db = new testContext())
            {

                // Find the record first
                var myemp = db.Employees.Find(3);
                Console.WriteLine("EmpID\t{0}",myemp.empid);
                Console.WriteLine("Firstname\t{0}", myemp.firstname);
                Console.WriteLine("Lastname\t{0}", myemp.lastname);

                // Update DbSet in memory
                myemp.lastname = "Smith";

                // Write to db
                db.SaveChanges();
                
                // db.SaveChanges is the same as the following RAW T-SQL
                //db.Database.ExecuteSqlCommand("update hr.employees set lastname='Smith' where empid=3");

                Console.WriteLine("Press any key to exit...");
                Console.ReadKey();
            }

How to Add a New Record

            using (var db = new testContext())
            {
                var newemp = new Employee();
                newemp.firstname = "Adam";
                newemp.lastname = "Smith";
                newemp.title="Economist";
                newemp.titleofcourtesy="";
                newemp.birthdate=Convert.ToDateTime("01/01/1980");
                newemp.hiredate=Convert.ToDateTime("01/01/2001");
                newemp.address="16 Bay Street";
                newemp.city="Toronto";
                newemp.region="Mr.";
                newemp.postalcode="B2C 2V7";
                newemp.country="CANADA";
                newemp.phone="(416) 822-2288";

                // Add to DbSet
                db.Employees.Add(newemp);
                // Write to db
                db.SaveChanges();

                // db.SaveChanges is the same as the following RAW T-SQL
                //db.Database.ExecuteSqlCommand("insert into hr.employees (..) values (...)");

                Console.WriteLine("Press any key to exit...");
                Console.ReadKey();
            }

How to Delete a Record

            using (var db = new testContext())
            {
                // identify the record first, (empid=10) is the new record inserted in last code snippet.
                var empToBeDeleted=db.Employees.Find(10);

                // remove from DbSet
                db.Employees.Remove(empToBeDeleted);

                // Write to db
                db.SaveChanges();

                // db.SaveChanges is the same as the following RAW T-SQL
                //db.Database.ExecuteSqlCommand("delete from hr.employees where empid=10");

                Console.WriteLine("Press any key to exit...");
                Console.ReadKey();
            }

Further Reading

  • Working with Entity Data from MSDN
  • Working with Objects
  • Working with Data (Entity Framework Tutorial)