"ChildViews" und Beziehungen

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Wenn zwischen Tabellen in einem DataSet Beziehungen vorhanden sind, können Sie eine DataView mit Zeilen aus der verwandten untergeordneten Tabelle erstellen, indem Sie die CreateChildView-Methode der DataRowView für die Zeilen in der übergeordneten Tabelle verwenden. Der folgende Code zeigt z. B. Categories und die verwandten Products in alphabetischer Reihenfolge an, die nach CategoryName und ProductName sortiert sind.

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"]);  
}

Siehe auch