problem with getting foreign key contraint name using DatabaseMetadata

Hi
I am trying to build a create SQL statement(DDL),
What i am doing is following
DatabaseMetaData dbm = conn.getMetaData();
ResultSet foreign = dbm.getImportedKeys(catalog,
schemaName, tableName);
String contraint = foreign.getString("PK_NAME");
But i am getting contraint as null, i know that for
this table there is a foreign key with a constraint
name?

What wrong am i doing?, is there any other parameter i
need to set?
Does anyone ever worked a utility which will create
DDL for all the tables in a collection, I tried using
iseries navigator, but it is not working as i need,
Ashish


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