C# を使用して MySQL でカスタム ストアド プロシージャ、トリガー、関数を作成する方法

DELIMITER //
CREATE PROCEDURE GetEmployeeByID(IN empID INT)
BEGIN
   SELECT * FROM Employees WHERE EmployeeID = empID;
END //
DELIMITER ;

using MySql.Data.MySqlClient;

MySqlConnection connection = new MySqlConnection("connectionString");
MySqlCommand command = new MySqlCommand("GetEmployeeByID", connection);
command.CommandType = CommandType.StoredProcedure;

command.Parameters.AddWithValue("@empID", 1);

connection.Open();
MySqlDataReader reader = command.ExecuteReader();

while (reader.Read())
{
    Console.WriteLine(reader["EmployeeName"]);
}

reader.Close();
connection.Close();

CREATE TRIGGER UpdateInventory AFTER INSERT ON Orders
FOR EACH ROW
BEGIN
   UPDATE Products SET Inventory = Inventory - NEW.Quantity WHERE ProductID = NEW.ProductID;
END

using MySql.Data.MySqlClient;

MySqlConnection connection = new MySqlConnection("connectionString");
MySqlCommand command = new MySqlCommand("INSERT INTO Orders (ProductID, Quantity) VALUES (1, 10)", connection);

connection.Open();
command.ExecuteNonQuery();
connection.Close();

CREATE FUNCTION CalculateDiscount(price DECIMAL(10,2), discount DECIMAL(10,2))
RETURNS DECIMAL(10,2)
RETURN price - (price * (discount / 100));

using MySql.Data.MySqlClient;

MySqlConnection connection = new MySqlConnection("connectionString");
MySqlCommand command = new MySqlCommand("SELECT CalculateDiscount(100, 10)", connection);

connection.Open();
object result = command.ExecuteScalar();
connection.Close();

Console.WriteLine(result);