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这本书的中文翻译质量还是很高的。但因为工作中都是英文环境，看英文原版的资料反而“更接地气”。

温故而知新，继续学习，继续提高才是王道！

PL/SQL's History and Background

Review Section
This section has presented the following details about the history and background of Oracle database:
1. Oracle evolved from Relational Software, Inc. (RSI), which evolved from Software Development Laboratories (SDL).
2. The SQL language is the interface to the Oracle Database 12c database engine, and Oracle extensions provide a competitive advantage.
3. The PL/SQL language extends the behavior of SQL and has enabled the evolution of object-relational technologies.
4. PL/SQL wraps access to embedded Java libraries.
5. PL/SQL makes possible the implementation of an object-relational Oracle database.
6. PL/SQL enables developers to exploit the Oracle Database 12c server.

Oracle Development Architecture

Review Section
This section has described the following points about Oracle database architecture:
1. SQL is the interface that lets you manage, maintain, and use the Oracle Database 12c database engine.
2. Oracle provides a SQL*Plus CLI and several GUIs that all interact with SQL and PL/SQL.
The SQL language is the “automatic transmission” to the data and many processes that keep the Oracle Database 12c database running smoothly. SQL replaces imperative languages as the interface to relational data and RDBMS management.
3. The two-tier model represents how SQL works with the data, with the SQL*Plus CLI or SQL GUI acting as the client and the database engine acting as the server.
4. The n-tier model represents how web-based applications engage the data through a middle tier, which can be three or more tiers in depth.

Mastery Check

The mastery check is a series of true-or-false and multiple-choice questions that let you confirm how well you understand the material in the chapter. You may check Appendix I for answers to these questions 

True or False:
1. ___Relational Software, Inc. became Oracle Corporation. (True)
2. ___Relational databases store information about how data is stored. (True)
3. ___Relational databases store data. (True)
4. ___SQL is an imperative language that lets you work in the Oracle database. (False)

(False. SQL is a set-based declarative language that lets you work in the Oracle database.)
5. ___The relational database model evolved from the object-relational database model. (False)
6. ___PL/SQL is the procedural extension of SQL. (True)
7. ___PL/SQL is an imperative language that is both event-driven and object-oriented. (True)
8. ___The Oracle database relies on an external Java Virtual Machine to run stored Java libraries. (False)
9. ___A two-tier model works between a browser and a database server. (False)
10. ___A three-tier model is a specialized form of an n-tier model. (True)

Multiple Choice:
11. Which of the following describes the roles of the Oracle listener? (Multiple answers possible) (AD)
A. Listen for incoming client requests
B. Send outgoing requests to client software
C. Forward requests to the PL/SQL engine
D. Forward requests to a SQL*Plus session
E. Forward requests to the SQL engine

12. Which of the following converts a relational model to an object-relational model? (CDE)
(Multiple answers possible)
A. A data catalog
B. A set of tables
C. An object data type
D. An imperative language that lets you build native object types
E. A JVM inside the database
13. SQL*Plus provides which of the following? (Multiple answers possible) (ABD)
A. An interactive mode
B. A call mode
C. A server mode
D. A client mode
E. All of the above
14. Which of the following is a capability of PL/SQL? (E)
A. Call SQL
B. Implement object types
C. Wrap C-callable programs
D. Wrap Java programs
E. All of the above
15. Which of the following are types of SQL statements? (Multiple answers possible) (ABCE)
A. Data Definition Language (DDL) statements
B. Data Manipulation Language (DML) statements
C. Data Control Language (DCL) statements
D. Create, replace, update, and delete (CRUD) statements
E. Transaction Control Language (TCL) statements