思想灵活
发表于 2025-3-23 13:10:04
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.
ungainly
发表于 2025-3-23 15:00:04
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不溶解
发表于 2025-3-23 20:55:54
The Database System EnvironmentThis chapter discusses the environment of a database system. The sections in this chapter are as follows.
infarct
发表于 2025-3-23 23:04:26
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.
Sad570
发表于 2025-3-24 03:42:24
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少量
发表于 2025-3-24 08:53:46
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要控制
发表于 2025-3-24 12:00:49
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).
疯狂
发表于 2025-3-24 17:11:25
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错
发表于 2025-3-24 22:10:56
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).
婚姻生活
发表于 2025-3-25 01:26:13
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.