In C# Global Connection To Be Used In All Classes

I've a connection string saved to Properties.Settings.Default, i need to use an sql connection in all classes without having to declare it everytime, so how should it be declared?

Solution 1:

You actually don't need to use a single SqlConnection everywhere. A better approach would be to create a class to manage you data access. Typically this is the duty of your Data Access Layer (DAL). DAL is a set of classes that handle all the database related stuff.

A very simple class for this purpose could be something like this:

publicclassDatabaseManager
{
    privatestatic DatabaseManager _instance;
    privateDatabaseManager()
    {
    }

    staticDatabaseManager()
    {
        _instance = new DatabaseManager();
    }

    public DatabaseManager Instance
    {
        get { return _instance; }
    }

    privatestringGetConnectionString()
    {
        return Properties.Settings.Default.MyConnectionString;
    }

    public SqlConnection CreateConnection()
    {
        returnnew SqlConnection(GetConnectionString());
    }
}

You can extend this class to contain another methods to execute your queries.

I highly recommend you to use an ORM (Object-Relational Mapper) like Entity Framework.

Solution 2:

It can be done with the help of STATIC variable in any class

Solution 3:

Whenever you instantiate a new object pass to its constructor a reference to that connection.

Solution 4:

I've have something similar set up in an old project like so. It's worth noting that you should always be using a new SqlConnection for all your operations, because of connection pooling.

public staticclassSqlConnectionUtil
{
    public staticstring DefaultConnectionString { get; private set; }

    staticSqlConnectionUtil()
    {
        SqlConnectionUril.DefaultConnectionString = 
                Properties.Settings.Default.TheConnectionString;
    }

    public static SqlConnection Create()
    {
        return new SqlConnection(SqlConnectionUtil.DefaultConnectionString);
    }
}

You would then use it like this.

using (var connection = SqlConnectionUtil.Create())
{
    using (var command = connection.CreateCommand())
    {
        // do things.
    }
}