Problems creating a one-to-one relationship with an access database in c#

Question

I am trying to create a one to one relationship in a Microsoft Access database using c#. So far, I have the following code which (from what I understand) should create a one-to-one relationship:

OleDbConnection dbCon = new OleDbConnection("Provider = Microsoft.Jet.OLEDB.4.0; Data Source = d:\\Test.mdb; Jet OLEDB:System Database=c:\\secure.mdw; User Id=321; Password=123;");
dbCon.Open();
String szTable1 = "CREATE TABLE Table1 (Field1 int UNIQUE NOT NULL PRIMARY KEY)";
OleDbCommand table1Cmd = new OleDbCommand(szTable1, dbCon);
table1Cmd.ExecuteNonQuery();    
String szTable2 = "CREATE TABLE Tablea (Fielda int UNIQUE NOT NULL PRIMARY KEY)";
OleDbCommand table2Cmd = new OleDbCommand(szTable2, dbCon);
table2Cmd.ExecuteNonQuery();
String szRelationship1 = "ALTER TABLE Table1 ADD CONSTRAINT TableLink FOREIGN KEY (Field1) REFERENCES Tablea(Fielda) ON DELETE CASCADE";
OleDbCommand relationship1Cmd = new OleDbCommand(szRelationship1, dbCon);
relationship1Cmd.ExecuteNonQuery();
dbCon.Close();

This creates the 2 tables and creates a relationship between them, but when I look at the MSysRelationship table in Access, it is giving me a grbit of 4096 (which would be one-to-many) instead of 4097 which is one-to-one:

_{(source: richardn.co.uk )}

When I look at the relationship in the relationships window, it is showing me on the relationship diagram that it is a one-to-many relationship, but in the edit relationship window it is saying it is a one-to-one relationship:

_{(source: richardn.co.uk )}

I'm really stuck here because in Access if I edit the relationship and change one of the settings and click on ok, it instantly becomes a one-to-one relationship in the window and the grbit changes to 4097. What am I missing in my code to set the relationship up as a one-to-one with a grbit of 4097 originally?

Answer 1

As suggested by my answer to a similar question here , this appears to be a glitch in the way relationships are displayed in the Relationships tab when the relationship is created using DDL. In that previous answer I didn't go so far as to change something in the "Edit Relationships" dialog and see if the little line in the Relationships tab actually changed, but your findings indicate that it does.

I don't believe that you are doing anything wrong , and the "fix" would be to tweak the MSysRelationships.grbit value, but you can't get at the [MSys...] tables from an OleDb connection anyway. So, this might simply be one of those little quirks we have to accept.

And really, if the relationship actually behaves as a One-to-One then it doesn't really matter what the little line in the Relationships tab looks like. Run a couple of tests to ensure that the relationship and the Referential Integrity rules behave as they should, and if they do, then just move on to other things.