On Mon, 9 Feb 2004, Tuan Luu wrote: > Example: > > Table 1: > Inventory, Productnr, Productserial > (PK Inventory, Prouctnr) > > Table 2: > Pruductnr, Produktdesc, Productversion > (PK Productnr; FK Productnr) > > This Construct gives me an error during the creation in Postgresql > (saying there is no unique constraint matching given keys for referenced > table xxxx). The Primary Key in table 1 consists of two columns. In the > second table there is a foreign key refencing to the first table. > > A unique constraint doesn't make sense on table one. Am I missing > something here?
What are the semantics you are looking for? Foreign keys only can refer to unique things, because except for a few odd cases involving nulls and match partial, it's intended that one particular row is being referenced. If there are multiple rows in table1 with a particular productnr, how do you want a reference to that to act (esp in the case of delete or update to table 1). ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match