Reusing database connection with Dapper in .NET Web API
The code is misleading. You're not actually creating a new connection when you do this in most circumstances. By default pooling is enabled for a connection unless you explicitly tell it not to.
I'm not 100% certain of the exact criteria behind pooling, but the gist of it is that if you reuse the same connection string rapidly in your code, pooling should only actually create one connection from your app to SQL Server, instead of creating a new connection every time you do
new SqlConnection and open it.
By disposing of the connection, you're basically signaling that that particular usage is finished....so the logic behind maintaining the pool can know that you're done with that particular connection. Again I don't know exactly how pooling is implemented, but I imagine it's internally keeping track of how many connections from your code are made so it can decide whether to keep an actual connection to SQL Server open or not.