Master/Detail Relationship -- dotnet windows forms databinding

dotnet windows forms databinding : Master/Detail Relationship

Chuck P
10/23/2006 2:31:02 PM

I have a dataset (dsIntake) in the designer with a master/detail relation.
The relation is marked with Relation Only and Nested Relation

In the designer code it is:
this.relationIntakes_vwIntakeRelatedCases = new
System.Data.DataRelation("Intakes_vwIntakeRelatedCases", new
System.Data.DataColumn[] {
this.tableIntakes.IntakeIDColumn}, new
System.Data.DataColumn[] {
this.tablevwIntakeRelatedCases.IntakeIDColumn},
false);

In my save event I have

intakesTableAdapter.Update(dsIntake); //master
vwIntakeRelatedCasesTableAdapter.Update(dsIntake); //detail

To test I added one row to the master and one to the detail and tried to
save it.

If I debug break after the first update and look at the dataset.
I see the Intakes table does have the PrimaryKey (IntakeID) column is filled
with the correct value from the database (autonumber). If I look at the
detail table vwIntakeRelatedCases, the PrimaryKey from the master table
(IntakeID) column is 0.

When I step through the second update I get an exception:
{"The INSERT statement conflicted with the FOREIGN KEY constraint
\"IntakeRelatedCases_IntakeID_fk\". The conflict occurred in database
\"WITS\", table \"SR.Intakes\", column 'IntakeID'.\r\nThe statement has been
terminated."}

I don't know how the FK in the detail column is suppose to be populated.

ALTER PROCEDURE [SR].[Intakes_Ins]
(
@DateOfIntake datetime,
@IncidentSummary varchar(2000)
)
AS
SET NOCOUNT OFF;
INSERT INTO [SR].[Intakes] ([DateOfIntake], [IncidentSummary]) VALUES
(@DateOfIntake, @IncidentSummary);

SELECT * FROM SR.Intakes WHERE (IntakeID = SCOPE_IDENTITY())

================================================

ALTER PROCEDURE [SR].[IntakeRelatedCases_Ins]
(
@IntakeID int,
@CaseID varchar(20)
)
AS
SET NOCOUNT OFF;
DECLARE @WitsID int

SELECT @WitsID = (SELECT WitsID FROM SR.Cases WHERE CaseID = @CaseID)

if @WitsID is null
begin
raiserror('CaseID does not exist',11,1)
return
end
else
begin
INSERT INTO [SR].[IntakeRelatedCases] ([IntakeID], [WitsID]) VALUES
(@IntakeID, @WitsID);

SELECT * FROM SR.vwIntakeRelatedCases WHERE (IntakeRelatedCaseID =
SCOPE_IDENTITY())
end
====================================================

v-lliu NO[at]SPAM online.microsoft.com
10/24/2006 12:00:00 AM

Hi Chuck,

[quoted text, click to view]

The FK contraint is violated at the database level in this scenario. The
exception occurs because there is no value 0 of the IntakeID column in the
master table while you are attempting to insert a new row with value 0 of
the IntakeID column into the detail table.

If you mark the relation between the two datatable in the dataset with
'Both Relation and Foreign Key Constraint' or 'Foreign Key Constraint
Only', an exception will occur even when you add such a new row with value
0 of the IntakeID column into the detail datatable, because FK constraint
is enabled in the dataset level.

It seems that the IntakeID column in the master table is auto-increment,
which means that only after the new row is saved in the database, the
IntakeID column gets a real value from the database. We should get the
value of the IntakeID column at this time and set it to the new row of the
detail datatable.

We have two options to do it. One option is to get the value of the
IntakeID column from the new added row directly and the other option is to
set the parent-child relationship between the parent row and child row. As
for the option 2, the DataRelation will automatically cascade the primary
key value down to the related child rows. The following is the sample code
for the two options.

// The datatable 'State' is a master table and 'City' is a detail table
// The third column in the City is the foreign key

DataRow stateRow = this.dataSet11.State.NewRow();
stateRow[1] = "aaa";
this.dataSet11.State.Rows.Add(stateRow);

DataSet1TableAdapters.StateTableAdapter stateAdapter = new
DataSet1TableAdapters.StateTableAdapter();
stateAdapter.Update(stateRow);

DataRow cityRow = this.dataSet11.City.NewRow();
// option 2 of setting a relation between the parent row and child row
cityRow.SetParentRow(stateRow);
cityRow[0] = 1;
cityRow[1] = "bbb";
// option 1 of getting the value of the primary key directly and setting it
into the child row
cityRow[2] = stateRow[0];
this.dataSet11.City.Rows.Add(cityRow);

DataSet1TableAdapters.CityTableAdapter cityAdapter = new
DataSet1TableAdapters.CityTableAdapter();
cityAdapter.Update(cityRow);

this.dataSet11.AcceptChanges();

Hope this helps.
If you have anything unclear or need our further assistance, please feel
free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support

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Chuck P
10/24/2006 6:30:02 AM

I thought the pages of code hidden in the dataset designer was going to
automatically set the foreign key.

[quoted text, click to view]

v-lliu NO[at]SPAM online.microsoft.com
10/25/2006 12:00:00 AM

Hi Chuck,

Thank you for your prompt response.

The dataset.Designer.cs file contains the code for the DataSet. It is
consistent with what you see in the designer.

Is the problem solved now? If not, please feel free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support

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