Error: MySQL - operand should contain 1 column.

Question

This query works when I type it directly into MySQL, but not in C#.

double deltaTime = (DateTime.Now - collectTime).TotalSeconds;


string query = String.Format("UPDATE buildings LEFT JOIN server_buildings ON buildings.global_id = server_buildings.global_id AND buildings.level = server_buildings.level SET buildings.storage = buildings.storage (server_buildings.speed * {0} * IF(buildings. boost >= NOW(), 2, 1)) WHERE buildings.global_id IN('generator', 'test')", deltaTime / 3600d);

Just got the error MySQL - operand should contain 1 column. Thanks for the suggestion! :)

It is expected to increase in value in "storage" over time.

Answer 1

I'm relatively new to MySQL. This is a query with parameters.

string query = String.Format("UPDATE buildings JOIN server_buildings ON buildings.global_id = server_buildings.global_id AND buildings.level = server_buildings.level SET buildings.storage = buildings.storage + (server_buildings.speed * ?Num * IF(buildings.boost >= NOW(), 2, 1)) WHERE buildings.global_id IN('generator', 'test')");
                     
            using (MySqlCommand command = new MySqlCommand(query, connection))
            {
                MySqlParameter param = new MySqlParameter("?Num", (deltaTime / 3600d));
                command.Parameters.Add(param);
      
               command.ExecuteNonQuery();
            }