rel-ops.txt

来自「ssd7 exercise 1 ,绝对有用~欢迎下载」· 文本 代码 · 共 20 行

1
SELECT Title,Price
FROM BOOK 
WHERE PublisherID IN (SELECT PublisherID
                      FROM PUBLISHER
	              WHERE Name = "Thomas Connolly" OR Name = "Lippman"); 

2
SELECT Name
FROM PUBLISHER, BOOK
WHERE PublisherID IN (SELECT PublisherID
                      FROM BOOK
                      WHERE 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 "Thomas Connolly" or "Lippman".

I use the same relational operation to know a publisher which has special book,select the Name from the table PUBLISHER when its PUBILSHERID is selected in the table BOOK,whose Title is "Database Systems".