c# - System.Data.SqlClient.SqlException nvarchar 为 float

Question

我正在使用以下代码更新我的表格:

 private void AddToQuotation()
    {
        con.Open();
        cmd = new SqlCommand(@"update JobQuotations
                                set    quo_discount     = @discount
                                ,      quo_unitPrice   = @unitPrice
                                ,      quo_TotalAmount = @totalAmount
                                ,      quo_finishing   = @finishing
                                where  quo_custname    = @customername
                                and    quo_verified    = 'Yes'", con);

        cmd.Parameters.AddWithValue("@customername",DropDownList3.SelectedItem.Value.ToString());
        cmd.Parameters.AddWithValue("@discount",txtDisc.Text);
        cmd.Parameters.AddWithValue("@unitPrice",txtUnitPrice.Text);

        cmd.Parameters.AddWithValue("@finishing",txtFinishing.Text);
        cmd.Parameters.AddWithValue("@totalAmount",lblTotalAmount.Text);
        cmd.ExecuteNonQuery();
        con.Close();
        string script = "alert(\"Functioning!\");";

        ScriptManager.RegisterStartupScript(this, GetType(),
            "ServerControlScript", script, true);
    }

我不断收到此错误:

An exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll but was not handled in user code

Additional information: Error converting data type nvarchar.

这段代码上次对我有用。我不知道发生了什么。

Answer 1

我建议您使用SqlDbType并将每个参数放入数据库中相应的类型，如下所示:

cmd.Parameters.Add (new SqlParameter("@unitPrice", SqlDbType.Float).Value = txtUnitPrice.Text ;

或

cmd.Parameters.AddWithValue("@unitPrice", SqlDbType.Float).Value = txtUnitPrice.Text;