rel-ops.txt

来自「SSD7（数据库系统原理）Exercise 1」· 文本 代码 · 共 8 行

In order to perform this query, I used two operations: 
1.the project operation;
2.the select operation.

The role of each operation in this query:
1.The project operation will selects the attributes of table which here we should select the "Title" and "Price" of table BOOK.
2.The select operation will selects the rows in table which here we should satisfy that the publisher should be either "Addison Wesley" or 
"McGraw Hill".