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DB2 Connection string with SSL Server Certificate on .NET (Core)

I have been attempting to set up a DB2 Connection programmatically, via .NET, and I've puzzled with the following findings:
1. Testing a connection on VS Code
After installing the Db2 Connect extension, I've populated the following fields:
Database Name;
Host;
Port;
UserID;
Password;
and set the Checkbox Enable SSL Security = true, in addition to populating the full path of the SSL Server Certificated (saved on my local drive C:\...crt).
As a result, the Db2 connection has been established.
2. Testing a connection programmatically
After adding IBM.Data.DB2.Core as a reference into the project through NuGet, I've used in a Controller:
using System;
using IBM.Data.DB2.Core;
namespace SSLTest
{
class Program
{
static void Main()
{
DB2Command MyDB2Command = null;
String MyDb2ConnectionString = "database=alias;uid=userid;pwd=password;"; // nub of
//the issue
DB2Connection MyDb2Connection = new DB2Connection(MyDb2ConnectionString);
MyDb2Connection.Open();
MyDB2Command = MyDb2Connection.CreateCommand();
MyDB2Command.CommandText = "SELECT * from d.Test";
...
MyDb2DataReader.Close();
MyDB2Command.Dispose();
MyDb2Connection.Close();
}
}
}
To fully replicate programmatically the connection settings described in 1., I've used:
String MyDb2ConnectionString = "DATABASE=xxxxx;SERVER=xxxxx;UID=xxxx;PWD=xxxx;Security=SSL";
where SERVER = Hostand wonder on the way to add the SSL Server pathinto the connection string. Otherwise the connection would keep failing.
Thanks in advance.
Best

Store user-specific connection strings for later use in ASP.NET Web API

I am working on complicated project which allows every client to set their connection string information to connect to their own database but after that I didn't now what to do or how to let the client reach his own connection string (I don't have a table to save the connection string I want to be dynamic).
Is there any way to store the connection string in config page for every client and read those page in my web config.

If number of client is managable, then you store it in web config file and you need seperate dbContext implentation if everyones database is different. If same db design is same for all, you can store credentials in dictionary and dynamically prepare connection string run time and connect.
Here is an example for MSSQL (I assume you are not using EF)
Not need to store connectionstring in web config.
Prepare connection string. You can store user wise parameters in DB as well.
public string BuildConnectionString(string dataSource, string dbName, string userId, string password,
string persistSecurityInfo, string encrypt, string trustServerCertificate, string applicationIntent, string multiSubnetFailover)
{
return $"Data Source = {dataSource}; Initial Catalog = {dbName}; User ID = {userId}; Password = {password}; " +
$"Persist Security Info = {persistSecurityInfo}; Encrypt = {encrypt}; TrustServerCertificate = {trustServerCertificate};" +
$" ApplicationIntent = {applicationIntent}; MultiSubnetFailover ={multiSubnetFailover}";
}
DB Connection example:
void CheckDbConnection()
{
string connetionString = BuildConnectionString("WIN-50GP30FGO75", // or IP
"Demodb", "YourUserID", "YourPassword", "True", "False", "False",
"ReadWrite", "False");
string sql = "Select TutorialID,TutorialName from table1";
using (SqlConnection cnn = new SqlConnection(connetionString))
{
using (SqlCommand command = new SqlCommand(sql, cnn))
{
cnn.Open();
dataReader = sqlquery.ExecuteReader();
while (dataReader.Read())
{
Output = Output + dataReader.GetValue(0) + "-" +
dataReader.GetValue(1) + "</br>";
}
Console.Write(Output);
cnn.Close();
}
}
}

You wont be able overwrite or add something to the Web.config during runtime, only read from it.The web.config file is only read once during startup and wont be used afterwards.
A suggestiong to overcome this is either store the connectionstring for your customers in your own database or store them somewhere else. I prefer using Azure KeyVault for these things, as it allows you to let the user change the data using a specific key.
Also this is one of those scenarios where security is a big factor, so you must be very carefull when giving your customers these kinds of actions.

How to set a EF code first connection string at runtime

I'm missing something. I have a small project where I am trying to insert some data into a database. When I created the model I used Code First against an existing database. I wanted to make the app capable of point to any server at runtime. This is a down and dirty utility app an and running internally but I need some flexibility when running it.
From reading some msdn articles I saw where I could extend the DBContext on initialization so I did the following:
added a parameter to the initialization:
public OtherEventModel(string ConnectionString)
: base("name=OtherEventModel")
{...
Then within my code I built the connection string based upon the properties passed in from the UI:
private OtherEventModel ConnectToServer(string server, string username, string password)
{
try
{
SqlConnectionStringBuilder sqlBuilder = new SqlConnectionStringBuilder
{
DataSource = server,
UserID = username,
Password = password,
InitialCatalog = "My_Database",
IntegratedSecurity = true
};
var connection = sqlBuilder.ToString();
ModelContext = new OtherEventModel(connection);
return ModelContext;
}
catch (Exception ex)
{
throw new Exception(string.Format("Error connecting to server {0}", ex.Message));
}
I can see the connection string created however when I run the code I receive an exception that the connection string (what should be in app.config could not be found). Which I do not have a connection string or key within app config since I was trying to inject the connection string in at runtime.
Error:
Error inserting data No connection string named 'OtherEventModel' could be found in the application config file
I was under the impression from what I have read that Code first uses a standard SQL connection string and does not require the EntityConnectionStringBuild (used for object first dev)
Can someone point me in the right direction as to what I have missed or what I am doing wrong.
Thanks in advance

You're almost there, just pass the connection string to the base:
public OtherEventModel(string ConnectionString)
: base(ConnectionString)
Make sure you comment the throw line in the method below. Unfortunately you have to do this again every time you update the model.

Change Database during runtime in Entity Framework, without changing the Connection

I have a server that hosts 50 databases with identical schemas, and I want to start using Entity Framework in our next version.
I don't need a new connection for each of those databases. The privileges of the one connection can talk to all of the 50 databases, and for data management and speed (this is a WebAPI application) I don't want to instantiate a new EF context every time I talk to each of the databases if I don't have to, unless of course if this occurs each time a request comes to the server then no big deal.
All I really need is the ability to change the USE [databasename] command, which I assume eventually gets sent to the server from EF.
Is there a way to accomplish this in code? Does EF maintain a read/write property in the Context that refers to the database name that could be changed on the fly before calling SaveChanges(), etc.??
Thank you!!!
bob

Don't Work hard, work smart !!!!
MYContext localhostContext = new MYContext();
MYContext LiveContext = new MYContext();
//If your databases in different servers
LiveContext.Database.Connection.ConnectionString = LiveContext.Database.Connection.ConnectionString.Replace("localhost", "Live");
//If your databases have different Names
LiveContext.Database.Connection.ConnectionString = LiveContext.Database.Connection.ConnectionString.Replace("DBName-Localhost", "DBName-Live");
the structure for databases should be the same ;)

You can take a look at:
SO question about passing existing SQL Connection to
EntityFramework Context
and at this article describing how to
change database on existing connection.
Please let me know if any additional help is needed.
Edited
Updated 2nd link to point to SqlConnection.ChangeDatabase method.
So eventually code would look similarly to the following:
MetadataWorkspace workspace = new MetadataWorkspace(
new string[] { "res://*/" },
new Assembly[] { Assembly.GetExecutingAssembly() });
using (SqlConnection sqlConnection = new SqlConnection(connectionString))
using (EntityConnection entityConnection = new EntityConnection(workspace, sqlConnection))
using (NorthwindEntities context = new NorthwindEntities(entityConnection))
{
// do whatever on default database
foreach (var product in context.Products)
{
Console.WriteLine(product.ProductName);
}
// switch database
sqlConnection.ChangeDatabase("Northwind");
Console.WriteLine("Database: {0}", connection.Database);
}

It is very simple
I had
public WMSEntities() : base("name=WMSEntities") //WMSEntities is conection string name in web.config also the name of EntityFramework
{
}
already in autogenerated Model.Context.cs of edmx folder.
To connect to multiple database in runtime, I created another constructor that takes connection string as parameter like below in same file Model.Context.cs
public WMSEntities(string connStringName)
: base("name=" + connStringName)
{
}
Now, I added other connection string in Web.Config for example
<add name="WMSEntities31" connectionString="data source=TESTDBSERVER_NAME;initial catalog=TESTDB;userid=TestUser;password=TestUserPW/>
<add name="WMSEntities" connectionString="data source=TESTDBSERVER_NAME12;initial catalog=TESTDB12;userid=TestUser12;password=TestUserPW12/>
Then, when connecting to database I call below method passing connectionString name as parameter
public static List<v_POVendor> GetPOVendorList(string connectionStringName)
{
using (WMSEntities db = new WMSEntities(connectionStringName))
{
vendorList = db.v_POVendor.ToList();
}
}

Here's my solution for just changing the database name. Simply pull the string from the web or app.config file, modify it, and then instantiate:
string yourConnection = ConfigurationManager.ConnectionStrings["MyEntities"].ConnectionString.Replace("MyDatabase", yourDatabaseName);
dcon = new MyEntities(yourConnection);

I have implemented this in my current project in which we have a common security database and different database for every client in the project. So our security database has a table that contain connection string for every other database. We just pass client id and get the connection string of the client database..
For this add two EDMX one for the common database and other for common schema databases. When user login or what might be your scenario to choose database go to common databse and get the connection string and create object of the needed database. Here is Code sample any, if any quer let me know..
You can keep connection string regarding every other database in a table in a a common database shared by all the other database.
EntityInstance_ReviewEntities.GetContext(GetConnectionString(ClientId));
private string GetConnectionString(int TenantId)
{
EntityConnectionStringBuilder entityBuilder = new EntityConnectionStringBuilder();
ISecurityRepository objSecurity = new SecurityRepository();
string tenantConnectionString = objSecurity.GetClientConnectionString(TenantId);
entityBuilder.ProviderConnectionString = tenantConnectionString;
entityBuilder.Provider = "System.Data.SqlClient";
entityBuilder.Metadata = #"res://*/ClientEntity.YourEntity.csdl|res://*/ClientEntity.ADBClientEntity.ssdl|res://*/ClientEntity.YourEntity.msl";
return entityBuilder.ToString();
}

EntityConnection.ChangeDatabase method is not supported, but SqlConnection.ChangeDatabase works fine.
So you have to use SqlConnection in entity framework database's constructor:
using MvcMyDefaultDatabase.Models;
using System.Data.Metadata.Edm;
using System.Data.SqlClient;
using System.Data.EntityClient;
using System.Configuration;
using System.Reflection;
public ActionResult List(string Schema)
{
SqlConnection sqlConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString);
MetadataWorkspace workspace = new MetadataWorkspace(new string[] { "res://*/" }, new Assembly[] { Assembly.GetExecutingAssembly() });
EntityConnection entityConnection = new EntityConnection(workspace, sqlConnection);
sqlConnection.Open();
sqlConnection.ChangeDatabase(Schema);
Models.MyEntities db = new MyEntities(entityConnection);
List<MyTableRecords> MyTableRecordsList = db.MyTableRecords.ToList();
return View(MyTableRecordsList);
}
With this code you can read the tables with the same format (same table name and same fields) of several schema passing the database name in the "Schema" string.

For SQL Server, if you want to change only the database, not a connection, try:
public class XXXXDbContext : DbContext
{
public string databaseName
{
set
{
Database.GetDbConnection().Open();
Database.GetDbConnection().ChangeDatabase(value);
}
}
}

Moving connection string from app.config to code in C#

I'm trying to use Entity Framework and it put it's connection string into app.config. I would like to move it to code as it's easier for me at this stage of development.
metadata=res://*/database.csdl|res://*/database.ssdl|res://*/database.msl;provider=System.Data.SqlClient;provider connection string="data source=computer;initial catalog=database;persist security info=True;user id=user;password=Mabm#A;multipleactiveresultsets=True;App=EntityFramework"
How can I make Entity Framework use connection string from code rather then look at the app.config? Alternatively if it's not possible how can I pass parameters to app.config (like dbname, dbuser, dbpassword)?

You can use EntityConnectionStringBuilder for this purpose.
Check here
public string GetConnectionString()
{
string connectionString = new EntityConnectionStringBuilder
{
Metadata = "res://*/Data.System.csdl|res://*/Data.System.ssdl|res://*/Data.System.msl",
Provider = "System.Data.SqlClient",
ProviderConnectionString = new SqlConnectionStringBuilder
{
InitialCatalog = ConfigurationManager.AppSettings["SystemDBName"],
DataSource = ConfigurationManager.AppSettings["SystemDBServerName"],
IntegratedSecurity = false,
UserID = ConfigurationManager.AppSettings["SystemDBUsername"],
Password = ConfigurationManager.AppSettings["SystemDBPassword"],
MultipleActiveResultSets = true,
}.ConnectionString
}.ConnectionString;
return connectionString;
}

When you create an instance of your ObjectContext derived class, you can simply pass the connection string as a constructor argument.

Rather than use a username and password, why not use Integrated Security? It is more secure and easier to manage.
i.e. 'Trusted_Connection = Yes' in your connection string and securely manage access through AD.
Connection Strings

First, create your context using the constructor with the connectionString parameter.
http://msdn.microsoft.com/en-us/library/gg679467(v=vs.103).aspx
Note that it's not directly this constructor that you must call, but the specific inherited context constructor for your database that your Entity generator created for you.
Furthermore, if you want to pass the username and password at runtime, you can create a connection string using this class:
http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnectionstringbuilder.aspx
See here:
http://msdn.microsoft.com/en-us/library/bb738533.aspx

If the connection string log in details are always the same then I would suggest that you use ConfigurationManager to retrieve the connection string from your app.config and encrypt the ConnectionStrings section of the file.