I open one database at the start, then need to open another database based on user selecting two values. The database selection has to be at run-time and will change every time.
Have tried to access the Connection String using the Connection String class and have tried other options like Singleton which I do not understand. I am running this on a local Windows 10 system running SQL Server Express. Am coding using Asp.Net Core 2.1
> ASP.Net Core v2.1
Building multi tenant, multi year application
Every client will have one SQL DATABASE per year
I hope to have a table with the following structure
COMPANY_CODE VARCHAR(3),
COMPANY_YEAR INT,
COMPANY_DBNAME VARCHAR(5)
Sample Data
COMPANY_CODE: AAD
COMPANY_YEAR: 19
COMPANY_DB: AAD19
COMPANY_CODE: AAD
COMPANY_YEAR: 18
COMPANY_DB: AAD18
COMPANY_CODE: AAD
COMPANY_YEAR: 17
COMPANY_DB: AAD17
So, every company will multiple rows - one for each financial year.
The COMPANY_DB column will store the DB name to open for that session.
Once the user is authenticated, I want to change the connection string to point to the database in the COMPANY_DB column of the selected row and then let the logged in user perform transactions.
I am unable to figure out how to change the connection string that is embedded in startup.cs.
Any tips on how to achieve this will be most appreciated.
I figured out that you are using one DbContext class for each database. See here for more information: docs.
Remove AddDbContext from Startup, remove OnConfiguring from DbContext and pass options to the constructor.
public class BloggingContext : DbContext
{
public BloggingContext(DbContextOptions<BloggingContext> options)
: base(options)
{ }
public DbSet<Blog> Blogs { get; set; }
}
Then, write service providing DbContext:
public interface IBlogContextProvider
{
BlogContext GetBlogContext(string connectionString);
}
public class BlogContextProvider : IBlogContextProvider
{
BlogContext GetBlogContext(string connectionString)
{
var optionsBuilder = new DbContextOptionsBuilder<BloggingContext>();
optionsBuilder.UseSqlServer(connectionString);
return new BlogContext(optionsBuilder);
}
}
Add service in your Startup.cs:
services.AddScoped<IBlogContextProvider, BlogContextProvider>();
Now you can use DI:
public class HomeController : Controller
{
private IBlogContextProvider _provider;
public HomeController(IBlogContextProvider provider)
{
_provider = provider;
}
public ActionResult Index()
{
using (var context = _provider.GetBlogContext(<your connection string>))
{
//your code here
}
return View();
}
}
EDIT: Of course, you can write ContextProvider as generic.
I used this pluralsight video on MVC code first migrations to keep my default MVC IdentityDb context and create another context for custom tables. Since then I get an error trying to connect connecting to the database online:
CREATE DATABASE permission denied in database 'master'.
.........
It works locally. My connection string are correct and my context classes point to the right connection string name:
public class IdentityDb : IdentityDbContext<ApplicationUser>
{
public IdentityDb()
: base("DefaultConnection", throwIfV1Schema: false)
{
}
public static IdentityDb Create()
{
return new IdentityDb();
}
}
public class CustomDb : DbContext
{
public CustomDb() : base("DefaultConnection") { }
public DbSet<Inquiry> Inquiry { get; set; }
public DbSet<Product> Product { get; set; }
}
Connection string:
<add name="DefaultConnection" connectionString="server=***.db.1and1.com; initial catalog=***;uid=***;pwd=***" providerName="System.Data.SqlClient" />
I've read that the connection string name should be the same as the context class name but since I have two contexts I need a common name (DefaultConnection) which I've specified in the contexts.
It works connecting to my local database but not when its online so I did wonder if this would relate to the migration history table being up to date online and EF 6 trying to update the database but the entries in the migrations table match.
Any help appreciated.
* UPDATE *
I tried resetting the EF migrations with this guide thinking if the migrations where out of sync with the online DB it could result in EF trying to re-create the database causing this issue. However the problem still persists!
I have now added these lines to my context constructors respectively:
Database.SetInitializer<IdentityDb>(null);
Database.SetInitializer<CustomDb>(null);
This has stopped the error but kind of defeated the purpose of EF because I now have to remove it when creating migrations and manually script the changes to the online DB, then put it back in for the site to work online.
I'm trying to insert some rows into Filemaker using Script Component. I followed this article Creating an ODBC Destination with the Script Component
When I edit the script here I set the connection string:
public override void AcquireConnections(object Transaction)
{
string connectionString;
//connectionString = this.Connections.FmConnection.ConnectionString;
odbcConn = new OdbcConnection("uid=someUID;Dsn=FM;pwd=somepassword");
odbcConn.Open();
}
I get the connection string from the this.Connections object and set it to the new OdbcConnection object. This does not work as I keep getting the exception. I tried setting the connection string manually as you can see above. I still get the exception.
In other parts of my package I use the connection manager to Filemaker and it works. Just not in this script component.
The exceptions I'm getting is:
Error at MyPackageName: [Filemaker] Password Incorrect
What is wrong?
I've a C# 4.0 console application and a SQL Server 2008 database up and running on database server.
Does somebody know if there is a way to get the database properties (like "Database Read-Only" ) from the C# code?
My guess is it should be, but I was not able to find out the accurate solution.
Thanks in advance
There are at least two ways to do it. One is to use the Database Metadata tables the other to use SQL Management objects in both cases there's lot of data there so you really need to know what you want. For example this is how you would get the "Database Read-Only" property you mentioned.
Using a SqlCommand against the MetaData
using (SqlConnection cnn = new SqlConnection("Data Source=.;Initial Catalog=master;Integrated Security=SSPI;"))
{
SqlCommand cmd = new SqlCommand("SELECT is_read_only FROM sys.filegroups",cnn);
cnn.Open();
var isReadOnly = cmd.ExecuteScalar();
Console.WriteLine(isReadOnly );
}
Using SMO
using System;
using Microsoft.SqlServer.Management.Smo;
namespace SMO_Test
{
class Program
{
static void Main(string[] args)
{
Server srv = new Server(); //Connection to the local SQL Server
Database db = srv.Databases["master"];
foreach (FileGroup fg in db.FileGroups)
{
Console.WriteLine(fg.ReadOnly);
}
}
}
}
Having this simple code I get "Cannot drop database "test_db" because it is currently in use" (CleanUp method) as I run it.
[TestFixture]
public class ClientRepositoryTest
{
private const string CONNECTION_STRING = "Data Source=.;Initial Catalog=test_db;Trusted_Connection=True";
private DataContext _dataCntx;
[SetUp]
public void Init()
{
Database.SetInitializer(new DropCreateDatabaseAlways<DataContext>());
_dataCntx = new DataContext(CONNECTION_STRING);
_dataCntx.Database.Initialize(true);
}
[TearDown]
public void CleanUp()
{
_dataCntx.Dispose();
Database.Delete(CONNECTION_STRING);
}
}
DataContext has one property like this
public DbSet<Client> Clients { get; set; }
How can force my code to remove database?
Thanks
The problem is that your application probably still holds some connection to the database (or another application holds connection as well). Database cannot be deleted where there is any other opened connection. The first problem can be probably solved by turning connection pooling off (add Pooling=false to your connection string) or clear the pool before you delete the database (by calling SqlConnection.ClearAllPools()).
Both problems can be solved by forcing database to delete but for that you need custom database initializer where you switch the database to single user mode and after that delete it. Here is some example how to achieve that.
I was going crazy with this! I have an open database connection inside SQL Server Management Studio (SSMS) and a table query open to see the result of some unit tests. When re-running the tests inside Visual Studio I want it to drop the database always EVEN IF the connection is open in SSMS.
Here's the definitive way to get rid of Cannot drop database because it is currently in use:
Entity Framework Database Initialization
The trick is to override InitializeDatabase method inside the custom Initializer.
Copied relevant part here for the sake of good DUPLICATION... :)
If the database already exist, you may stumble into the case of having
an error. The exception “Cannot drop database because it is currently
in use” can raise. This problem occurs when an active connection
remains connected to the database that it is in the process of being
deleted. A trick is to override the InitializeDatabase method and to
alter the database. This tell the database to close all connection and
if a transaction is open to rollback this one.
public class CustomInitializer<T> : DropCreateDatabaseAlways<YourContext>
{
public override void InitializeDatabase(YourContext context)
{
context.Database.ExecuteSqlCommand(TransactionalBehavior.DoNotEnsureTransaction
, string.Format("ALTER DATABASE [{0}] SET SINGLE_USER WITH ROLLBACK IMMEDIATE", context.Database.Connection.Database));
base.InitializeDatabase(context);
}
protected override void Seed(YourContext context)
{
// Seed code goes here...
base.Seed(context);
}
}
This is a really aggressive database (re)initializer for EF code-first with migrations; use it at your peril but it seems to run pretty repeatably for me. It will;
Forcibly disconnect any other clients from the DB
Delete the DB.
Rebuild the DB with migrations and runs the Seed method
Take ages! (watch the timeout limit for your test framework; a default 60 second timeout might not be enough)
Here's the class;
public class DropCreateAndMigrateDatabaseInitializer<TContext, TMigrationsConfiguration>: IDatabaseInitializer<TContext>
where TContext: DbContext
where TMigrationsConfiguration : System.Data.Entity.Migrations.DbMigrationsConfiguration<TContext>, new()
{
public void InitializeDatabase(TContext context)
{
if (context.Database.Exists())
{
// set the database to SINGLE_USER so it can be dropped
context.Database.ExecuteSqlCommand(TransactionalBehavior.DoNotEnsureTransaction, "ALTER DATABASE [" + context.Database.Connection.Database + "] SET SINGLE_USER WITH ROLLBACK IMMEDIATE");
// drop the database
context.Database.ExecuteSqlCommand(TransactionalBehavior.DoNotEnsureTransaction, "USE master DROP DATABASE [" + context.Database.Connection.Database + "]");
}
var migrator = new MigrateDatabaseToLatestVersion<TContext, TMigrationsConfiguration>();
migrator.InitializeDatabase(context);
}
}
Use it like this;
public static void ResetDb()
{
// rebuild the database
Console.WriteLine("Rebuilding the test database");
var initializer = new DropCreateAndMigrateDatabaseInitializer<MyContext, MyEfProject.Migrations.Configuration>();
Database.SetInitializer<MyContext>initializer);
using (var ctx = new MyContext())
{
ctx.Database.Initialize(force: true);
}
}
I also use Ladislav Mrnka's 'Pooling=false' trick, but I'm not sure if it's required or just a belt-and-braces measure. It'll certainly contribute to slowing down the test more.
None of those solutions worked for me. I ended up writing an extension method that works:
private static void KillConnectionsToTheDatabase(this Database database)
{
var databaseName = database.Connection.Database;
const string sqlFormat = #"
USE master;
DECLARE #databaseName VARCHAR(50);
SET #databaseName = '{0}';
declare #kill varchar(8000) = '';
select #kill=#kill+'kill '+convert(varchar(5),spid)+';'
from master..sysprocesses
where dbid=db_id(#databaseName);
exec (#kill);";
var sql = string.Format(sqlFormat, databaseName);
using (var command = database.Connection.CreateCommand())
{
command.CommandText = sql;
command.CommandType = CommandType.Text;
command.Connection.Open();
command.ExecuteNonQuery();
command.Connection.Close();
}
}
I try adding Pooling=false like Ladislav Mrnka said but always got the error.
I'm using Sql Server Management Studio and even if I close all the connection, I get the error.
If I close Sql Server Management Studio then the Database is deleted :)
Hope this can helps
I got the same error. In my case, I just closed the connection to the database and then re-connected once the in my case the new model was added and a new controller was scaffolded. That is however a very simple solution and not recommended for all scenarios if you want to keep your data.
I got the same problem back then. Turns out the solution is to close the connection in Server Explorer tab in Visual Studio. So maybe you could check whether the connection is still open in the Server Explorer.
Its simple because u're still using the same db somewhere, or a connection is still open.
So just execute "USE master" first (if exist, but usually is) and then drop the other db. This always should work!
Grz John