I want to print the sum of price coloum of SQL in C# using class and form

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I am making a store managment system using database sql server and i am putting products using form cashout and i want to print a sum of all products in textbox then i set sum statement in sql and their coloum name bill is a sum and now i want to send the sum of products from class to form. but there is error Cannot implicitly convert type 'float' to 'System.Data.DataTable' .please help i am begineer. i want urgent answer.

What I have tried:

C#

public DataTable slectbill()
        {

            string query = "select sum(subTotal) as bill from Cashout";

            SqlDataAdapter adapt = new SqlDataAdapter(query, connection());

            openConnection();
            DataTable dt = new DataTable();
            DataRow row = dt.Rows[0];
            bill = row["bill"].ToString();
            adapt.Fill(dt);
            closeConnection();

            return bill;
        }

Posted 9-Aug-20 13:52pm

John Daid

Updated 9-Aug-20 18:41pm

Patrice T

v3

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Garth J Lancaster · Answer 1 · 2020-08-09T15:39:00

"i am begineer" - ok
"i want urgent answer" - not ok - people on this site are volunteers, ie do not get paid - we are not your servants - I suggest you learn some manners

I can't see why you're complicating things with a datatable - you seem to want a straightforward decimal (money) result back, so off the top of my head, wouldn't something like this

public Decimal slectbill(string connString)
{
    Decimal bill = 0;
    string query = "select sum(subTotal) as bill from Cashout";

    using (SqlConnection conn = new SqlConnection(connString))
    {
        SqlCommand cmd = new SqlCommand(sql, conn);
        try
        {
            conn.Open();
            bill = (Decimal)cmd.ExecuteScalar();
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
    return bill;
}

make more/better sense ?

lightindark7007 · Answer 2 · 2020-08-09T18:41:00

Solution 2

If you want to get a single value from ADO query it is not suitable to use

SqlDataAdapter

prefer using SQLCommand with Scalar value calling

sqlCommand.ExecuteScalar()

Posted 9-Aug-20 18:41pm

lightindark7007