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Check Database ConnectionState

I'm connecting to Firebird Database using C#
I can't find where to check the ConnectionState to the database
If I make new fbConnection inside project it's easy to check it by fbConnection.ConnectionState
but I have made this connection with wizard and it's saved in App.config file
I tried to use System.Configuration.ConfigurationManager but it doesn't have ConnectionState
So how can I check connection state that defined in App.config file.

It seems that you don't understand how this thing (the connection) works or what it is. The ConfigurationManager class just helps you to retrieve the connectionstring (note the word string. It is just a string nothing more).
With this string you can build your real instance of an FBConnection and try to open that connection. Now you could check the ConnectionState.
So
string connectionString = ConfigurationManager.ConnectionStrings["MyConnection"].ConnectionString;
using(FbConnection myConnection = new FbConnection(connectionString))
{
// At this point the myConnection instance is certainly closed so
// it is total useless to check the ConnectionState
myConnection.Open();
// At this point the myConnection instance is certainly opened,
// otherwise you get an exception and your code cannot contine,
// so also here it is useless to check the ConnectionState
// however...
if(myConnection.ConnectionState == ConnectionState.Open)
{
.... do your stuff with the connection.....
}
}
For this code to work you need to have in your App.Config the appropriate section where you store the details required to connect to your database under the symbolic name "MyConnection"
<connectionStrings>
<add name="MyConnection" connectionString="Data Source=localhost;
Database=YourDatabaseFile.fdb;
User=YourUserName;
Password=????whatever???;
Pooling=True" />
</connectionStrings>
So I really have never needed to check the connection state of a connection. The only possible use if this property is when you want to keep a global connection instance and in various part of your code you need to check the ConnectionState before trying to open or close this global instance. This scenario is not the best way to work with a disposable object like the connection that should be opened for the shortest period of time possible and the immediately destroyed (disposed) And exiting from the using block disposes the connection.

Check out this link, it may be useful for you.
https://sourceforge.net/p/firebird/NETProvider/ci/0475d606c597498a99be50393646c1c92d773dd4/tree/examples/ASP.NET/web.config

Best way to handle connection when calling a function from a Console App or SQLCLR object with ("Context Connection=true")

I have the following type of code in my data layer, which can be called from a console app, windows app, etc, with the proper connection string being read from the corresponding caller's App.Config file:
public static udsDataset GetDataset(int datasetID)
{
string connectionString =
ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
string sql = #"select * from Dataset WHERE DatasetID=#datasetID";
using (SqlConnection conn = new SqlConnection(connectionString))
{
// Dapper query:
return conn.Query<udsDataset>(sql, new {datasetID } ).First();
}
}
I now want to call this same code from a SQLCLR stored procedure (within the database where these tables exist), where you would typically use a context connection:
using(SqlConnection connection = new SqlConnection("context connection=true"))
{
connection.Open();
// etc etc etc
}
The most obvious approach that comes to mind is to overload the function:
public static udsDataset GetDataset(int datasetID)
{
string connectionString =
ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
using (SqlConnection conn = new SqlConnection(connectionString))
{
return GetDataset(datasetID, conn);
}
}
public static udsDataset GetDataset(int datasetID, SqlConnection conn)
{
// caller is responsible for closing and disposing connection
string sql = #"select * from Dataset WHERE DatasetID=#datasetID";
return conn.Query<udsDataset>(sql, new {datasetID } ).First();
}
So apps with an App.Config could call the connection-less version and SQLCLR could call the version requiring a SqlConnection.
This "seems ok", but having to write the exact same style of overload for every single similar function makes it feel wrong.

Taking the question (and comments on it) at face-value, why do you need:
the option of passing in an existing connection when calling from a SQLCLR procedure
? You should treat the Context Connection the same as any other connection with regards to Open and Dispose. It sounds like you are thinking that the SqlConnection, when using a Connection String of "Context Connection = true;", needs to be opened only once and then not disposed until completely done, whereas you would Open / Dispose of it several times otherwise. I don't see any reason to have differing behavior in these two scenarios.
All of that aside, how to best handle detecting the change in environment (between Console App and SQLCLR object)? You have two choices, both being probably easier than you are expecting:
Make no changes to the app code, but rely on an additional config file:
You can create a file named sqlservr.exe.Config in the C:\Program Files\Microsoft SQL Server\MSSQL{SqlVersion}.{SqlServerInstanceName}\MSSQL\Binn folder (e.g. C:\Program Files\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\Binn, where the 11 in MSSQL11 is for SQL Server 2012). The format of this file, as should probably be expected, is as follows:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<connectionStrings>
<add name="CoolioAppDB" connectionString="Context Connection = true;" />
</connectionStrings>
</configuration>
This might be considered "cleaner" code, but does introduce an external dependency that your DBA might be ok with, might dislike but tolerate, or might ask your manager to write you up for ;-).
Make a very minor change to the app code, but don't rely on an additional config file:
You can easily auto-detect whether or not you are currently running in SQL Servers's CLR host by using the IsAvailable property of the SqlContext class. Just update your original code as follows:
string connectionString = "Context Connection = true;"; // default = SQLCLR connection
if (!SqlContext.IsAvailable) // if not running within SQL Server, get from config file
{
connectionString =
ConfigurationManager.ConnectionStrings["CoolioAppDB"].ConnectionString;
}
This usage, by the way, is noted in the "Remarks" section of that linked MSDN page for the IsAvailable property.

MongoDB C# changing replica set config

I am using the C# driver to work with MongoDB. I need to use my program to update the set config during execution, and then allow other parts of the program to continue using the driver.
My current issue is reconfiguring the driver to use the new set.
try
{
var res = Database.Admin.RunCommand(new CommandDocument("replSetReconfig", replicaSetConfig));
}
catch (EndOfStreamException){}
catch (Exception e)
{
Log.Exc("Problem updating replica set", e);
ranCommand = false;
}
if (ranCommand)
{
HERE - I need to update the MongoClient or MongoServer to have the new servers
return;
}
I assume when an EndOfStreamException occurs, that the command has been successful, as the server has shutdown/started a reconfig.
I'd like to update the driver to have the new config to ensure that it will definitely reconnect to at least one of the servers, in any edge cases where changing the config will prevent it connecting back with its original connection string.
Is there any way to achieve this?
As an extra question, is there any way from C# to determine the current replica set config version?
Thanks

I can answer part 2 of your question - you can query the local database to get the current replica set configuration:
MongoServer server = client.GetServer();
var local = server.GetDatabase("local");
var collection = local.GetCollection("system.replset");
var cfg = collection.FindOne();
Console.WriteLine(cfg["version"]);
I would imagine that if the original connection string is no longer valid, you need to create a new MongoClient object with a new connection string.
[Later]
You can also get everything else about the replica set, including its status, by running the replSetGetStatus command on the admin database.

DataDirectory Set up project

I am doing a SETUP project for a C# winforms, sqlite application.
Connection string seems to a bit of a problem. The user will put the Database he wants to work with at a location(which v will tell him). In this example it is "C:\\Program Files(x86)\\DefaultCompany\\RSetup"; The user can work his own copy of the DB.
So I am setting the data directory to this path in the Program.cs Main
This is the only way I can think of. If there is a better way thats grt!!.
App.config
<add name="ConnString" connectionString="|DataDirectory|\MySQlite.db;Compress=True;Version=3"
providerName="System.Data.Sqlite" />
Program.cs
Setting the datadirectory to the path of the executable. Currently hard coded the path of the executable
static void Main()
{
AppDomain.CurrentDomain.SetData("DataDirectory","C:\\Program Files(x86)\\DefaultCompany\\RSetup");
This doesn't seem to be working. It doesn't give any error except the data is not blank. Doesn't seem to be working in both set up and the regular project
Thank you
JC

You could ask the user where the database is located, store that path somewhere (such as User Settings) and then you can retrieve it at any time. This would give the user more flexibility of where to put it and multiple users on the same machine could have their own database if desired.
Here is some pseudocode...
string dbLocation = Properties.Settings.Default.DatabaseLocation;
if (string.IsNullOrWhiteSpace(dbLocation)
{
dbLocation = AskUserForLocation();
Properties.Settings.Default.DatabaseLocation = dbLocation;
Properties.Settings.Default.Save();
}
AppDomain.CurrentDomain.SetData("DataDirectory",dbLocation);
Using this approach you could also add a menu option to allow the user to change the location if desired.
It also gives you the ability to retrieve the value anywhere, including where you create a connection, you can append the path to the location between where you read the connection string and you create a new connection.
SQLiteConnection myConnection = new SQLiteConnection;();
myConnection.ConnectionString = Path.Combine(Properties.Settings.Default.DatabaseLocation, myConnectionString);
myConnection.Open();

How do I Programmatically change Connection String un LINQ C# Winforms

This question may be redundant, but i could not totally understand how to do this.
I need to be able to, when the users Run my Winforms app, can search for the instance of SQL if the previous one are not available. I already have the check for the DB existence, and also made a dialog wich search for all the available instance, and bulding the connection string isn't a problem. The point here is that, I need to be able to everytime the users open the app it loads the CN from a external file, and if the external file doesn't exist or the instance isn't available, i can use the app in another instance (asuming, offcourse, that the required DB is in that Instance).
The point is that, i don't know how to Programmatically change Connection String, using LINQ in winforms.
Thanks in advance

You should be to pass the connection string to the DataContext constructor.
var db = new MyDataContext(myconnectionstring);

var someConnectionString = "This is my connection String";
using (var db = new SomeConcreteDataContext(someConnectionString)){
//...Do whatever...
}

A DataContext is created per 'unit of work'.
As ichiban says pass the required connection string into the constructor when creating the DC