Titlebook: Database Systems; A Pragmatic Approach Elvis C. Foster,Shripad Godbole Book 2016Latest edition Elvis C. Foster and Shripad Godbole 2016 Rel

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The Edgier Waters of the Era: Gordon Burn’s Every reputable DBMS contains a system catalog (also called the data dictionary) of some form. This has been mentioned several times earlier in the course. This chapter discusses this very important component of the database system. The chapter proceeds under the following subtopics.

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不溶解

The Database System EnvironmentThis chapter discusses the environment of a database system. The sections in this chapter are as follows.

infarct

The Relational ModelThis chapter introduces you to the fundamental principles and concepts upon which subsequent chapters will be built. Discussion advances under the following sections.

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少量

要控制

Relational CalculusIn relational calculus, we simply specify what data is required, not how to obtain the required relation(s). Relational algebra, on the other hand, provides a collection of explicit operations in SELECT, JOIN, PROJECT etc., which can be used to tell the system how to derive desired relation(s).

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SQL Data Manipulation StatementsThere are four core DML statements in SQL, namely INSERT, UPDATE, DELETE, and SELECT. These statements apply to base tables and views (views will be discussed in the next chapter).

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Logical Views and System SecurityTwo very powerful and important features of SQL are the facility to create and manage logical views, and the capability to manage security issues of a database. This chapter discusses these two related issues.