TAILIEUCHUNG - Lecture Database system concepts (6/e): Chapter 3 - Silberschatz, Korth, Sudarshan

Chapter 3 introduction to SQL. This chapter presents the following content: Data definition, basic query structure, set operations, aggregate functions, null values, nested subqueries, complex queries, views, modification of the database. | Chapter 3: Introduction to SQL Database System Concepts, 6th Ed. ©Silberschatz, Korth and Sudarshan See for conditions on re-use Chapter 3: Introduction to SQL Overview of the SQL Query Language Data Definition Basic Query Structure Additional Basic Operations Set Operations Null Values Aggregate Functions Nested Subqueries Modification of the Database Database System Concepts - 6th Edition ©Silberschatz, Korth and Sudarshan History IBM Sequel language developed as part of System R project at the IBM San Jose Research Laboratory Renamed Structured Query Language (SQL) ANSI and ISO standard SQL: SQL-86, SQL-89, SQL-92 SQL:1999, SQL:2003, SQL:2008 Commercial systems offer most, if not all, SQL-92 features, plus varying feature sets from later standards and special proprietary features. Not all examples here may work on your particular system. Database System Concepts - 6th Edition ©Silberschatz, Korth and Sudarshan Data Definition Language The SQL data-definition language (DDL) allows the specification of information about relations, including: The schema for each relation. The domain of values associated with each attribute. Integrity constraints And as we will see later, also other information such as The set of indices to be maintained for each relations. Security and authorization information for each relation. The physical storage structure of each relation on disk. Database System Concepts - 6th Edition ©Silberschatz, Korth and Sudarshan Domain Types in SQL char(n). Fixed length character string, with user-specified length n. varchar(n). Variable length character strings, with user-specified maximum length n. int. Integer (a finite subset of the integers that is machinedependent). smallint. Small integer (a machine-dependent subset of the integer domain type). numeric(p,d). Fixed point number, with user-specified precision of p digits, with n

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