Sharing Db Connection Across POCOs in ASP.NET 5 (vNext) - asp.net

Question

I'm learning how to use ASP.NET 5 (vNext). In an attempt to do this, I'm working on a basic application. In this application, I'm trying to connect to the database from a couple of POCOs (Customer, Order, etc.) using Dapper. If I understand things correctly, its expensive to create, connect to, and tear down connections to a database. If this is true, I'm trying to figure out the recommended way to share a connection across multiple objects.
Currently, I have the following:
public class Order
{
private IDbConnection _connection;
public void Save()
{
using (_connection = new SqlConnection("[MyConnectionString]")
{
_connection.Open();
_connection.Execute("[INSERTION SQL]");
}
}
public List<Order> FindByCustomerEmailAddress(string emailAddress)
{
using (_connection = new SqlConnection("[MyConnectionString]")
{
_connection.Open();
return _connection.Query<List<Order>>("SELECT o.* FROM Order o, Customer c WHERE o.CustomerId=c.CustomerId AND c.EmailAddress='" + emailAddress + "'" );
}
}
}
public class Customer
{
private IDbConnection _connection;
public void Save()
{
using (_connection = new SqlConnection("[MyConnectionString]")
{
_connection.Open();
_connection.Execute("[INSERTION SQL]");
}
}
public Customer FindByEmailAddress(string emailAddress)
{
using (_connection = new SqlConnection("[MyConnectionString]")
{
_connection.Open();
return _connection.Query<Customer>("SELECT * FROM Customer WHERE EmailAddress='" + emailAddress + "'" );
}
}
}
I thought about creating a Database class that looks like this:
public static class Database
{
private static IDbConnection Connection { get; set; }
public static IDbConnection GetConnection()
{
if (Connection == null)
{
Connection = new SqlConnection("[MyConnectionString]");
Connection.Open();
}
return Connection;
}
}
public class Order
{
public void Save()
{
var connection = Database.GetConnection();
connection.Execute("[INSERTION SQL]");
}
public List<Order> FindByCustomerEmailAddress(string emailAddress)
{
var connection = Database.GetConnection();
return connection.Query<List<Order>>("SELECT ...");
}
}
However, after thinking about this, I'm not sure if this a good strategy for managing a database connection. The use of static in this manner seems dangerous. Yet, it seems like someone has had to solve this issue. But, nothing I've seen is explained so I do not understand if it actually works. Can someone share with me what the recommended approach for managing database connections in an efficient manner is?
Thank you!

Answer 1

Opening and closing connection to a database server is indeed expensive. However, .NET implements connection pooling just for this reason, and it is on by default. You can modify the setting of how many connection it should keep open (I don't recall the default).
So, if your connection string is the same, .NET will reuse an open connection from the pool and use that. If different, it'll create a new one.
Your first code is correct in using "using" so when you're done, the dispose/close will give the connection back to the pool.
See more about this here; https://msdn.microsoft.com/en-us/library/8xx3tyca(v=vs.110).aspx