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子檢視和關聯

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如果 DataSet 的資料表之間存在關聯性，則可以使用 DataView 的 CreateChildView 方法，為父資料表的資料列建立 DataRowView (其包含來自相關子資料表的資料列)。 例如，下列程式碼顯示 Categories (類別) 及與其關聯的 Products (產品) (按 CategoryName 與 ProductName 字母順序排序)。

Dim catTable As DataTable = catDS.Tables("Categories")  
Dim prodTable As DataTable = catDS.Tables("Products")  
  
' Create a relation between the Categories and Products tables.  
Dim relation As DataRelation = catDS.Relations.Add("CatProdRel", _  
  catTable.Columns("CategoryID"), _  
  prodTable.Columns("CategoryID"))  
  
' Create DataViews for the Categories and Products tables.  
Dim catView As DataView = New DataView(catTable, "", _  
  "CategoryName", DataViewRowState.CurrentRows)  
Dim prodView As DataView  
  
' Iterate through the Categories table.  
Dim catDRV, prodDRV As DataRowView  
  
For Each catDRV In catView  
  Console.WriteLine(catDRV("CategoryName"))  
  
  ' Create a DataView of the child product records.  
  prodView = catDRV.CreateChildView(relation)  
  prodView.Sort = "ProductName"  
  
  For Each prodDRV In prodView  
    Console.WriteLine(vbTab & prodDRV("ProductName"))  
  Next  
Next  

DataTable catTable = catDS.Tables["Categories"];  
DataTable prodTable = catDS.Tables["Products"];  
  
// Create a relation between the Categories and Products tables.  
DataRelation relation = catDS.Relations.Add("CatProdRel",
  catTable.Columns["CategoryID"],  
                                                            prodTable.Columns["CategoryID"]);  
  
// Create DataViews for the Categories and Products tables.  
DataView catView = new DataView(catTable, "", "CategoryName",
  DataViewRowState.CurrentRows);  
DataView prodView;  
  
// Iterate through the Categories table.  
foreach (DataRowView catDRV in catView)  
{  
  Console.WriteLine(catDRV["CategoryName"]);  
  
  // Create a DataView of the child product records.  
  prodView = catDRV.CreateChildView(relation);  
  prodView.Sort = "ProductName";  
  
  foreach (DataRowView prodDRV in prodView)  
    Console.WriteLine("\t" + prodDRV["ProductName"]);  
}

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