rel-ops.txt

来自「ssd7 exercise 1 ,绝对有用~欢迎下载」· 文本 代码 · 共 19 行

1.
SELECT Title, Price
FROM BOOK
WHERE PublisherID IN (SELECT PublisherID
			FROM PUBLISHER
			WHERE Name = 'Electronics Industry' OR Name = 'NWPU Press');

2.
SELECT Name
FROM Publisher
WHERE PublisherID IN (SELECT PublisherID
			FROM Book
			WHERE Book.title = 'Database Systems');



I used select relational operation, which can return the special colomn of the table.
I select the price and title from the table book when its PublisherID is selected in the table publisher whose name is 'Electronics Industry' or 'NWPU Press'.
I use the same relational operation to know a publisher which has special book.