Update the First Row in a database C# mysql

Question

My problem is that:

I want to Select one row from the database, The data should be arrange in expiry (the ones that are not yet expired and I don't want to limit it). The items that passed the current date must be left alone. And with all the same ITEMID lets say I00001.
Then after selecting I want to Update the first row of the database. if the quantity reaches 0 then it will go the next row to update and so on.

Here is my example

Here is the current database screenshot.
I want select the itemid where = I00001 and deduct 50.
Then it should look like this
Then I want to arrange based on the expiry as I mentioned above.
Select the first row.
Deduct the 50 from the quantity. (as I also mentioned above).

Here is my code:

for (int i = 0; i < dataGridView.Rows.Count; i++)
{
    cmd = new MySqlCommand(@"SELECT * FROM inventory2 WHERE itemid = @itemid ORDER BY expiry ", sqlconnection);

    cmd = new MySqlCommand(@"UPDATE inventory2 SET quantity = @quantity WHERE itemid = @itemid ORDER BY expiry)", sqlconnection);

    sqlconnection.Open();
    cmd.ExecuteNonQuery();
    sqlconnection.Close();
}

I'm open for another suggestion in doing this. I hope you understand my problem. Thank you very much. I'm sorry I cannot send another screenshot.

I would do it all via sql without c# code. But it's 4am and I am off. Will look at it tomorrow — Drew
– Drew, Commented Sep 9, 2016 at 8:19

Berkay Yaylacı · Accepted Answer · 2016-09-09 11:50:26Z

1

Try this,

void UpdateQuantity() {
        // your connection string
        MySqlDataAdapter adp = new MySqlDataAdapter("Select * from table where ItemID = " + 13 + " Order BY expiry", cnn); // I have test db and I used it
        DataTable dt = new DataTable();
        adp.Fill(dt);
        int deductNum = 50;
        foreach (DataRow item in dt.Rows)
        {
            int value = (int)item["quantity"];
            if (value >= deductNum) // if had enough stock we don't need to pass the next line
            {
                int result = value - deductNum;
                item["quantity"] = result.ToString();
                break; // so need to exit from loop
            }
            else
            {
                deductNum -= value; // else we deduct value count from deduction
                item["quantity"] = 0; // quantity finished so it will be 0
            }
        }
        MySqlCommandBuilder cmb = new MySqlCommandBuilder(adp);
        adp.UpdateCommand = cmb.GetUpdateCommand();
        adp.Update(dt);
        dataGridView1.DataSource = dt; //to show the result
    }

(You can calculate :))

Hope helps,

answered Sep 9, 2016 at 11:50

Berkay Yaylacı

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3 Comments

Philip Over a year ago

Thank you. I owe you one

Philip Over a year ago

Hi! I got a chance to try your code but it displays an error. "Additional information: Specified cast is not valid." In int value = Convert.ToInt32((int)item["quantity"]);. Thanks :)

Berkay Yaylacı Over a year ago

I don't have Convert in my answer. Cast and Comvert together will give that error. @Philip

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