将列表框项目插入SQL数据库表，同时保持“身份”列不变

Question

I have the following code.

SqlConnection connection = new SqlConnection(@"Data Source = WOOLSVALLEG\MEGASUL; Initial Catalog = POSListDB2; Integrated Security = True");
for (int k = 0; k < listBox1.Items.Count; k++)
{
    SqlCommand command = new SqlCommand("INSERT INTO POStable2(L"+k+") Values(@L"+k+")", connection);
    command.CommandType = CommandType.Text;
    command.Connection = connection;
    command.Parameters.Clear();
    command.Parameters.AddWithValue("@L" + k +"", listBox1.Items[k].ToString());
    connection.Open();
    command.ExecuteNonQuery();
    connection.Close();
}

I want to insert each time an item of listbox into column of database table. I need identity column too. But the problem is it adds data diagonally as it updates each the loop iterate. How I can add for example 5 items from listbox into 5 columns of database table while the identity column remain same for the loop operation. Thanks

this is what I got;

Answer 1

You need to build a single insert statement and execute it only once. One way to do it is like this:

SqlCommand command = new SqlCommand();
command.CommandType = CommandType.Text;
command.Connection = connection;
command.Parameters.Clear();
var sql = "INSERT INTO POStable2(";
var values = "Values(";
for (int k = 0; k < listBox1.Items.Count; k++)
{
    sql = sql + "L" + k + ",";
    values = values + "@L" + k + ",";
    command.Parameters.AddWithValue("@L" + k +"", listBox1.Items[k].ToString());

}
sql = sql.TrimEnd(",") + ") " + values.TrimEnd(",") + ") ";
command.CommandText = sql;
connection.Open();
command.ExecuteNonQuery();
connection.Close();

I didn't test it, of course. You might want to put a brakepoint before opening the connection and check the sql you get.