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0a. The table tpurcdgives details of all products ordered. This table gives details of all purchase orders.

SELECT * FROM tcust, tpurcd, tprod WHERE tcust.code=tpurcd.cust AND tpurcd.prod=tprod.code

SELECT * FROM tcust, tpurcd, tprod WHERE tcust.code=tpurcd.cust AND tpurcd.prod=tprod.code

0b. Some of the tables are joined by a composite foreign key. For example to link shipment details to a shipment record we must join on (cust,shpd).

SELECT addr, tship.shpd, prod FROM tship, tshipd WHERE tshipd.cust=tship.cust AND tshipd.shpd=tship.shpd AND tship.addr IS NOT NULL

SELECT addr, tship.shpd, prod FROM tship, tshipd WHERE tshipd.cust=tship.cust AND tshipd.shpd=tship.shpd AND tship.addr IS NOT NULL