帮助我解决父母的问题 [英] Help me with my parent\Child tables issue

问题描述

Hello Guys

在我的Windows应用程序项目中，我正在使用数据集。有三张桌子：



产品

---------------

标题，身份证，价格



发票

---------------

ID，日期，描述



InvoiceItem

-------------- -

ID，Product_ID，Invoice_ID，Quantity



所有ID列都是Identity，tablename_ID格式列是外键。



在一个名为BuyForm的表单中，我得到所有输入，然后在Save_ButtonCLick中我想将这些信息插入到我提到的相关表中。

谷歌搜索我发现这篇文章：

插入关系使用DataSet和DataAdapter的数据

根据我从该文章中理解的内容，这是我的代码：

 DataRow invoice = DataSet .Tables [ 发票] NEWROW（）; 
 invoice [  Date] = DateConverter.ToPersianDate（）; 
 invoice [ 描述] =  string  .Empty; 
 DataSet.Tables [  Invoice]。Rows.Add（invoice）; 
 
 DataRow product =  null ; 
 DataRow invoiceItem =  null ; 
  foreach （DataGridViewRow row  in  ProductGridView.Rows）
 {
 product = DataSet.Tables [  Product]。NewRow（）; 
 invoiceItem = DataSet.Tables [  InvoiceItem]。NewRow（）; 
 
 product [  Title] = row.Cells [  ProductColumn]。Value.ToString（）; 
 product [  BuyPrice] = row.Cells [  BuyPriceColumn]。值; 
 product [  SellPrice] = row.Cells [  SellPriceColumn]。值; 
 invoiceItem [  Count] = row.Cells [  CountColumn]。值; 
 
 invoiceItem.SetParentRow（invoice）; 
 product.SetParentRow（发票）; 
 DataSet.Tables [  Product]。Rows.Add（product）; 
 DataSet.Tables [  InvoicItem]。Rows.Add（invoiceItem）; 
 
 TableAdapterManager.UpdateAll（DataSet）; 
} 

将invoiceItem添加到其DataTable时发生此错误：

 Column' Product_ID'不允许空值。

我应该如何更改我的代码？

谢谢

解决方案

您没有为InvoiceItem指定Product_Id并导致问题。 Identity字段仅用于主键，并且根据您的描述，Product_ID是外键，因此您必须以某种方式为其定义值。所以可能你应该有

 invoiceItem.SetParentRow（product）; 

作为旁注

 product.SetParentRow（发票）; 

看起来很奇怪，因为我怀疑发票是产品的母公司

Hello Guys
In my windows application project I am using Dataset. There are three tables:

Product
---------------
Title, ID, Price

Invoice
---------------
ID, Date, Description

InvoiceItem
---------------
ID, Product_ID, Invoice_ID, Quantity

All ID columnns are Identity and tablename_ID format columns are foreign Keys.

In a single form named BuyForm I get all inputs and then in a Save_ButtonCLick I want to Insert these information to the related tables I have mentioned.
After some googling I found this article:
Inserting relational data using DataSet and DataAdapter
Here is my code according to what I understand from that article:

DataRow invoice = DataSet.Tables["Invoice"].NewRow();
        invoice["Date"] = DateConverter.ToPersianDate();
        invoice["Description"] = string.Empty;
        DataSet.Tables["Invoice"].Rows.Add(invoice);
                    
        DataRow product = null;
        DataRow invoiceItem = null;
        foreach (DataGridViewRow row in ProductGridView.Rows)
        {
            product = DataSet.Tables["Product"].NewRow();
            invoiceItem = DataSet.Tables["InvoiceItem"].NewRow();
        
            product["Title"] = row.Cells["ProductColumn"].Value.ToString();
            product["BuyPrice"] = row.Cells["BuyPriceColumn"].Value;
            product["SellPrice"] = row.Cells["SellPriceColumn"].Value;
            invoiceItem["Count"] = row.Cells["CountColumn"].Value;
        
            invoiceItem.SetParentRow(invoice);
            product.SetParentRow(invoice);
            DataSet.Tables["Product"].Rows.Add(product);
            DataSet.Tables["InvoicItem"].Rows.Add(invoiceItem);
        
            TableAdapterManager.UpdateAll(DataSet);              
         }

This error occurs at time of adding invoiceItem to its DataTable:

Column 'Product_ID' does not allow nulls.

How should I change my code?
Thanks

解决方案

You don't specify the Product_Id for an InvoiceItem and that causes the problem. The Identity fields are used only for primary keys and based on you description, Product_ID is a foreign key so you must define the value for it, one way or another. So probably you should have

invoiceItem.SetParentRow(product);

As a side-note the row

product.SetParentRow(invoice);

looks odd since I doubt that invoice is a parent of product.

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