using System;

using Microsoft.Data.Sqlite;

namespace ScalarFunctionSample

{

class Program

{

static void Main()

{

var connection = new SqliteConnection("Data Source=:memory:");

connection.Open();

var createCommand = connection.CreateCommand();

createCommand.CommandText =

@"

CREATE TABLE cylinder (

name TEXT,

radius REAL,

height REAL

);

INSERT INTO cylinder

VALUES ('1x2', 1.0, 2.0),

('2x1', 2.0, 1.0);

";

createCommand.ExecuteNonQuery();

// SQLite will invoke this managed delegate. Debug it like you would any other code

// by setting breakpoints, etc.

connection.CreateFunction(

"volume",

(double radius, double height)

=> Math.PI * Math.Pow(radius, 2) * height);

var queryCommand = connection.CreateCommand();

queryCommand.CommandText =

@"

SELECT name,

volume(radius, height) AS volume

FROM cylinder

ORDER BY volume DESC

";

var reader = queryCommand.ExecuteReader();

while (reader.Read())

{

Console.WriteLine($"{reader["name"]}: {reader["volume"]}");

}

}

}

}