Data Integration

Integrated

SELECT red1.partnumber, (blue1.unitssold + red1.unitssold) AS "units sold" FROM red1, blue1
WHERE red1.partnumber = blue1.partnumber
UNION 
SELECT partnumber,  unitssold AS "units sold" FROM red1
WHERE partnumber not in (SELECT partnumber FROM blue1)
UNION
SELECT partnumber,  unitssold AS "units sold" FROM blue1
WHERE partnumber not in (SELECT partnumber FROM red1);

Non-integrated

First create a table where the descriptions appear to matchpart

CREATE TABLE matchpart (
blue2partnumber INTEGER,
red2partnumber INTEGER,
partdescription VARCHAR(20),
PRIMARY KEY (blue2partnumber, red2partnumber));

INSERT INTO matchpart VALUES (1,1009,'widget - 5cm');
INSERT INTO matchpart VALUES (2,1010,'widget - 10cm');
INSERT INTO matchpart VALUES (6,1006,'widget - blue');
INSERT INTO matchpart VALUES (8,1008,'widget - yellow');
INSERT INTO matchpart VALUES (16,1004,'widget - plain');

SELECT red2.partnumber, matchpart.partdescription, (blue2.unitssold + red2.unitssold) AS "units sold" FROM red2, matchpart, blue2
WHERE red2.partnumber = matchpart.red2partnumber
AND blue2.partnumber = matchpart.blue2partnumber
UNION 
SELECT partnumber, partdescription, unitssold AS "units sold" FROM red2
WHERE partnumber not in (SELECT red2partnumber FROM matchpart)
UNION
SELECT partnumber,  partdescription, unitssold AS "units sold" FROM blue2
WHERE partnumber not in (SELECT blue2partnumber FROM matchpart);