I'm trying to create a fail-safe insert. I have this working elsewhere
in the code, but this test statement keeps failing with the error:

'violation of PRIMARY or UNIQUE KEY constraint PK_DRUGQUANTITY on table
DRUGQUANTITY'

Statement:
INSERT INTO DRUGQUANTITY (NDC,QTY)
SELECT 123,456 FROM DRUGQUANTITY
WHERE NOT EXISTS (SELECT NDC FROM DRUGQUANTITY WHERE NDC=123);

Table and PK:
CREATE TABLE DRUGQUANTITY
(
NDC D_NDC NOT NULL,
QTY D_QUANTITY NOT NULL,
CONSTRAINT PK_DRUGQUANTITY PRIMARY KEY (NDC)
);

Why does this fail? I can substitute other table name's after the FROM,
but that fails too. Names for empty tables succeed, but no rows are
inserted.

Rick DeBay
Senior Software Developer
RxStrategies.net