用一个例子理解1NF,2NF,3NF,BCNF。。(此篇纯水,无价值) 设计一个论坛的数据库: (1) 用户:用户名,email,主页,电话,联系地址 (2) 帖子:发帖标题,发帖内容,回复标题,回复内容 第一次:将数据库设计为仅存在表。 create table1(用户名 email 主页 电话 联系地址 发帖标题 发帖内容 回复标题 回复内容) 很显然...
It is achieved by applying a set of rules and procedures to a database, known as normalization forms. There are several normalization forms, including the First Normal Form (1NF), Second Normal Form (2NF), Third Normal Form (3NF), Boyce-Codd Normal Form (BCNF), and the Fourth Normal ...
A. 1NF B. 2NF C. 3NF D. BCNF 查看完整题目与答案 通常按水在土壤中存在状态,下列哪种不属于土壤水类型。 A. 气/汽态水 B. 地下水 C. 固态水 D. 液态水 查看完整题目与答案 关于Student类下面说法正确的有() public class Student { int age; String name; public Student(){ }...
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College costs vary quite a bit, depending upon the type of school attended. For example, at many of the more expensive private schools, annual costs (including tuition, room, board, books, travel to and from home, and other expenses) may ex..