How to define mysql parameters min(date) and max(date)

Question

Hi everyone.

 

I'm semi-new from C# and i've never store objects from mysql query. In this case i've declared 2 Datetimes variables:

DateTime date_min
DateTime date_max

I'd like to define mysql Parameters max(date) and min(date) before the lopp from below query:

string query1 = "SELECT MIN(order_status.BEGIN_DATE) AS 'BEGIN DATE', MAX(order_status.END_DATE) AS 'END DATE' FROM project1.order_status INNER JOIN project1.orders ON orders.ID_ORDER = order_status.ID_ORDER WHERE orders.NUMBER_ORDER = 'TEST';";

I'd try like this for example: 

SqlParameter param  = new SqlParameter();
param.ParameterName = "@max_date";
param.Value = input_max_date;

Then i want to use like this:

string query1 = "SELECT @min_date AS 'BEGIN DATE', @max_date AS 'END DATE' FROM project1.order_status INNER JOIN project1.orders ON orders.ID_ORDER = order_status.ID_ORDER WHERE orders.NUMBER_ORDER = 'TEST';";

because of :

@min_date = MIN(order_status.BEGIN_DATE)
@max_date = MAX(order_status.END_DATE)

then i have the loop:

for (DateTime date = date_min; date <= date_max; date = date.AddDays(1))
    {
        var cmd = new MySqlCommand(query1, connection);

        string query2 = "SELECT COUNT(leave.ID_WORKER) AS 'NUMBER OF WORKERS ON LEAVE' FROM project1.leave WHERE DATE(leave.BEGIN_DATE) <= '"+date+"' AND DATE(leave.END_DATE) >= '"+date+"';";
        string query3 = "SELECT TIME_FORMAT(SEC_TO_TIME(SUM(TIME_TO_SEC(order_status.END_DATE) - TIME_TO_SEC(order_status.BEGIN_DATE))), '%H:%i:%s') AS 'TIME OF ALL ORDERS IN DAY' FROM project1.order_status INNER JOIN project1.orders ON orders.ID_ORDER = order_status.ID_ORDER WHERE (DATE(order_status.BEGIN_DATE) = '"+date+"' AND DATE(order_status.END_DATE) = '"+date+"');";
        string query4 = "SELECT TIME_FORMAT(SEC_TO_TIME(SUM(TIME_TO_SEC(order_status.END_DATE) - TIME_TO_SEC(order_status.BEGIN_DATE))), '%H:%i:%s') AS 'TIME OF ORDER IN DAY' FROM project1.order_status INNER JOIN project1.orders ON orders.ID_ORDER  = order_status.ID_ORDER WHERE (DATE(order_status.BEGIN_DATE) = '"+date+"' AND DATE(order_status.END_DATE) = '"+date+"') AND orders.NUMBER_ORDER = 'TEST';";

using (var command = new MySqlCommand(query1, connection))
                {
                    using (var reader1 = command.ExecuteReader())
                    {
                        while (reader1.Read())
                        {
                            date_min = Convert.ToDateTime(reader1[0]);
                            date_max = Convert.ToDateTime(reader1[1]);
                        }
                    }
                }
                var cmd1 = new MySqlCommand(query2, connection);
                var cmd2 = new MySqlCommand(query3, connection);
                var cmd3 = new MySqlCommand(query4, connection);
    }

Can someone please show what should kind of code lines should I write? maybe cmd.Parameters is enough? THX for any help.

 

There is my code:

 public partial class GenerateChartsOfOrders : Form
    {
        DateTime date_min;
        DateTime date_max;
        public GenerateChartsOfOrders()
        {
            InitializeComponent();
        }
        public void loaddata2()
        {
string query1 = "SELECT MIN(order_status.BEGIN_DATE) AS 'BEGIN DATE', MAX(order_status.END_DATE) AS 'END DATE' FROM project1.order_status INNER JOIN project1.orders ON orders.ID_ORDER = order_status.ID_ORDER WHERE orders.NUMBER_ORDER = 'TEST';";

            for (DateTime date = date_min; date <= date_max; date = date.AddDays(1))
            {
                var cmd = new MySqlCommand(query1, connection);

                string query2 = "SELECT COUNT(leave.ID_WORKER) AS 'NUMBER OF WORKERS ON LEAVE' FROM project1.leave WHERE DATE(leave.BEGIN_DATE) <= '"+date+"' AND DATE(leave.END_DATE) >= '"+date+"';";
                string query3 = "SELECT TIME_FORMAT(SEC_TO_TIME(SUM(TIME_TO_SEC(order_status.END_DATE) - TIME_TO_SEC(order_status.BEGIN_DATE))), '%H:%i:%s') AS 'TIME OF ALL ORDERS IN DAY' FROM project1.order_status INNER JOIN project1.orders ON orders.ID_ORDER = order_status.ID_ORDER WHERE (DATE(order_status.BEGIN_DATE) = '"+date+"' AND DATE(order_status.END_DATE) = '"+date+"');";
                string query4 = "SELECT TIME_FORMAT(SEC_TO_TIME(SUM(TIME_TO_SEC(order_status.END_DATE) - TIME_TO_SEC(order_status.BEGIN_DATE))), '%H:%i:%s') AS 'TIME OF ORDER IN DAY' FROM project1.order_status INNER JOIN project1.orders ON orders.ID_ORDER  = order_status.ID_ORDER WHERE (DATE(order_status.BEGIN_DATE) = '"+date+"' AND DATE(order_status.END_DATE) = '"+date+"') AND orders.NUMBER_ORDER = 'TEST';";

using (var command = new MySqlCommand(query1, connection))
                    {
                        using (var reader1 = command.ExecuteReader())
                        {
                            while (reader1.Read())
                            {
                                date_min = Convert.ToDateTime(reader1[0]);
                                date_max = Convert.ToDateTime(reader1[1]);
                            }
                        }
                    }

                    var cmd1 = new MySqlCommand(query2, connection);
                    var cmd2 = new MySqlCommand(query3, connection);
                    var cmd3 = new MySqlCommand(query4, connection);
            }
        }
    }