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POis it possible to add DataRelation to DataSet if child table contains rows that have no parent in parent table in C# / ADO.NET 2.0
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  1. POis it possible to add DataRelation to DataSet if child table contains rows that have no parent in parent table in C# / ADO.NET 2.0
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    copied!<p>If I fill the DataSet with DataAdapters that select all rows from Orders and Customers and call:</p> <pre> private void CreateRelation() { // Get the DataColumn objects from two DataTable objects // in a DataSet. Code to get the DataSet not shown here. DataColumn parentColumn = DataSet1.Tables["Customers"].Columns["CustID"]; DataColumn childColumn = DataSet1.Tables["Orders"].Columns["CustID"]; // Create DataRelation. DataRelation relCustOrder; relCustOrder = new DataRelation("CustomersOrders", parentColumn, childColumn); // Add the relation to the DataSet. DataSet1.Relations.Add(relCustOrder); } </pre> <p>(from <a href="http://msdn.microsoft.com/en-us/library/system.data.datarelation.aspx" rel="nofollow noreferrer">http://msdn.microsoft.com/en-us/library/system.data.datarelation.aspx</a>)</p> <p>there will be a runtime error if there is orders that do not have customers. This might happen when a buggy program has not deleted customer's orders when customer was deleted.</p> <p>What can I do except put Orders select string a additional where-condition:</p> <pre> CUSTID IN (SELECT DISTINCT CUSTID FROM CUSTOMERS) </pre> <p>OR: is it really that way (that all children have to have parents)? My code might have a bug also. The exception occurs when IN MY CODE I add the relation to filled DataSet. The exception is:</p> <p>An unhandled exception of type 'System.ArgumentException' occurred in System.Data.dll</p> <p>Additional information: This constraint cannot be enabled as not all values have corresponding parent values.</p> <p>Thanks &amp; Best Regards - Matti</p>
 

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