循环参数化查询

Question

我一直在寻找它的解决方案已有一段时间了，我在这里看到了类似的问题，但那里的答案并没有解决我的问题。在我的情况下，我想循环遍历datagridview值的行，将其插入MySql数据库。 datagridview中的行数取决于用户。当我尝试输入2行或更多行datagridview值并尝试将其插入数据库时​​，只成功插入第一行数据。

这是我的代码：

MySqlCommand cmd = new MySqlCommand();
                cmd.Connection = SecurityMod.dbconn();
                for (int i = 0; i < dgv_ctrl.Rows.Count; i++)
                {
                    string sql = "INSERT INTO delivery(DeliveryNumber, CreationDate, Client, Product, Price, Quantity, Total) " +
                             "VALUES(@num_Delivery, " + "@dgv_datevalue" + ", " +
                             "@name_Client" + ", " +
                             "@name_Product" + ", " +
                             "@priceof_Produt" + ", " +
                             "@quan_Product" + ", " +
                             "@price_Total" + ");";

                    cmd.Parameters.AddWithValue("@num_Delivery", num_Delivery);
                    cmd.Parameters.AddWithValue("@dgv_datevalue", DateTime.Parse(dgv_ctrl.Rows[i].Cells["Creation_Date"].Value.ToString()).ToString("yyyy-MM-dd HH:mm:ss"));
                    cmd.Parameters.AddWithValue("@name_Client", dgv_ctrl.Rows[i].Cells["Client_name"].Value);
                    cmd.Parameters.AddWithValue("@name_Product", dgv_ctrl.Rows[i].Cells["Product_name"].Value);
                    cmd.Parameters.AddWithValue("@priceof_Produt", dgv_ctrl.Rows[i].Cells["Price_ofProduct"].Value);
                    cmd.Parameters.AddWithValue("@quan_Product", dgv_ctrl.Rows[i].Cells["Quantity_ofProduct"].Value);
                    cmd.Parameters.AddWithValue("@price_Total", dgv_ctrl.Rows[i].Cells["Total_Price"].Value);
                    cmd.CommandText = sql;
                    cmd.ExecuteNonQuery();

错误：参数'@num_Delivery'已经定义。我是使用C＃语言的新手。任何想法和建议都会受到欢迎。

Answer 1

移动

MySqlCommand cmd = new MySqlCommand();

在for循环中：

string sql = "INSERT INTO delivery(DeliveryNumber, CreationDate, Client, Product, Price, Quantity, Total) " +
             "VALUES(@num_Delivery, " + "@dgv_datevalue" + ", " +
             "@name_Client" + ", " +
             "@name_Product" + ", " +
             "@priceof_Produt" + ", " +
             "@quan_Product" + ", " +
             "@price_Total" + ");";
for (int i = 0; i < dgv_ctrl.Rows.Count; i++)
{
    MySqlCommand cmd = new MySqlCommand();
    cmd.Connection = SecurityMod.dbconn();
    cmd.Parameters.AddWithValue("@num_Delivery", num_Delivery);
    cmd.Parameters.AddWithValue("@dgv_datevalue", DateTime.Parse(dgv_ctrl.Rows[i].Cells["Creation_Date"].Value.ToString()).ToString("yyyy-MM-dd HH:mm:ss"));
    cmd.Parameters.AddWithValue("@name_Client", dgv_ctrl.Rows[i].Cells["Client_name"].Value);
    cmd.Parameters.AddWithValue("@name_Product", dgv_ctrl.Rows[i].Cells["Product_name"].Value);
    cmd.Parameters.AddWithValue("@priceof_Produt", dgv_ctrl.Rows[i].Cells["Price_ofProduct"].Value);
    cmd.Parameters.AddWithValue("@quan_Product", dgv_ctrl.Rows[i].Cells["Quantity_ofProduct"].Value);
    cmd.Parameters.AddWithValue("@price_Total", dgv_ctrl.Rows[i].Cells["Total_Price"].Value);
    cmd.CommandText = sql;
    cmd.ExecuteNonQuery();
}

或清除其参数集合：

string sql = "INSERT INTO delivery(DeliveryNumber, CreationDate, Client, Product, Price, Quantity, Total) " +
             "VALUES(@num_Delivery, " + "@dgv_datevalue" + ", " +
             "@name_Client" + ", " +
             "@name_Product" + ", " +
             "@priceof_Produt" + ", " +
             "@quan_Product" + ", " +
             "@price_Total" + ");";
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = SecurityMod.dbconn();
for (int i = 0; i < dgv_ctrl.Rows.Count; i++)
{
    cmd.Parameters.Clear();
    cmd.Parameters.AddWithValue("@num_Delivery", num_Delivery);
    cmd.Parameters.AddWithValue("@dgv_datevalue", DateTime.Parse(dgv_ctrl.Rows[i].Cells["Creation_Date"].Value.ToString()).ToString("yyyy-MM-dd HH:mm:ss"));
    cmd.Parameters.AddWithValue("@name_Client", dgv_ctrl.Rows[i].Cells["Client_name"].Value);
    cmd.Parameters.AddWithValue("@name_Product", dgv_ctrl.Rows[i].Cells["Product_name"].Value);
    cmd.Parameters.AddWithValue("@priceof_Produt", dgv_ctrl.Rows[i].Cells["Price_ofProduct"].Value);
    cmd.Parameters.AddWithValue("@quan_Product", dgv_ctrl.Rows[i].Cells["Quantity_ofProduct"].Value);
    cmd.Parameters.AddWithValue("@price_Total", dgv_ctrl.Rows[i].Cells["Total_Price"].Value);
    cmd.CommandText = sql;
    cmd.ExecuteNonQuery();
}

Sql字符串可以不在循环中。

Answer 2

你可以这样做。它应该工作。

MySqlCommand cmd = new MySqlCommand();
cmd.Connection = SecurityMod.dbconn();
for (int i = 0; i < dgv_ctrl.Rows.Count; i++)
{
    string sql = "INSERT INTO delivery(DeliveryNumber, CreationDate, Client, Product, Price, Quantity, Total) " +
             "VALUES(@num_Delivery, " + "@dgv_datevalue" + ", " +
             "@name_Client" + ", " +
             "@name_Product" + ", " +
             "@priceof_Produt" + ", " +
             "@quan_Product" + ", " +
             "@price_Total" + ");";
    cmd.Parameter.Clear();
    cmd.Parameters.AddWithValue("@num_Delivery", num_Delivery);
    cmd.Parameters.AddWithValue("@dgv_datevalue", DateTime.Parse(dgv_ctrl.Rows[i].Cells["Creation_Date"].Value.ToString()).ToString("yyyy-MM-dd HH:mm:ss"));
    cmd.Parameters.AddWithValue("@name_Client", dgv_ctrl.Rows[i].Cells["Client_name"].Value);
    cmd.Parameters.AddWithValue("@name_Product", dgv_ctrl.Rows[i].Cells["Product_name"].Value);
    cmd.Parameters.AddWithValue("@priceof_Produt", dgv_ctrl.Rows[i].Cells["Price_ofProduct"].Value);
    cmd.Parameters.AddWithValue("@quan_Product", dgv_ctrl.Rows[i].Cells["Quantity_ofProduct"].Value);
    cmd.Parameters.AddWithValue("@price_Total", dgv_ctrl.Rows[i].Cells["Total_Price"].Value);
    cmd.CommandText = sql;
    cmd.ExecuteNonQuery();
}