ch3 - Database System Concepts, 5th Ed . Silberschatz,...

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Unformatted text preview: Database System Concepts, 5th Ed . Silberschatz, Korth and Sudarshan See www.db-book.com for conditions on re-use Chapter 3: SQL Chapter 3: SQL Silberschatz, Korth and Sudarshan 3.2 Database System Concepts, 5 th Edition, Oct 5, 2006 Chapter 3: SQL Chapter 3: SQL Data Definition Basic Query Structure Set Operations Aggregate Functions Null Values Nested Subqueries Complex Queries Views Modification of the Database Joined Relations** Silberschatz, Korth and Sudarshan 3.3 Database System Concepts, 5 th Edition, Oct 5, 2006 History 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: z SQL-86 z SQL-89 z SQL-92 z SQL:1999 (language name became Y2K compliant!) z SQL:2003 Commercial systems offer most, if not all, SQL-92 features, plus varying feature sets from later standards and special proprietary features. z Not all examples here may work on your particular system. Silberschatz, Korth and Sudarshan 3.4 Database System Concepts, 5 th Edition, Oct 5, 2006 Data Definition Language Data Definition Language The schema for each relation. The domain of values associated with each attribute. Integrity constraints 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. Allows the specification of not only a set of relations but also information about each relation, including: Silberschatz, Korth and Sudarshan 3.5 Database System Concepts, 5 th Edition, Oct 5, 2006 Domain Types in SQL 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 machine-dependent). 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 digits to the right of decimal point. real, double precision. Floating point and double-precision floating point numbers, with machine-dependent precision. float(n). Floating point number, with user-specified precision of at least n digits. More are covered in Chapter 4. Silberschatz, Korth and Sudarshan 3.6 Database System Concepts, 5 th Edition, Oct 5, 2006 Create Table Construct Create Table Construct An SQL relation is defined using the create table command: create table r ( A 1 D 1 , A 2 D 2 , ..., A n D n , (integrity-constraint 1 ), ..., (integrity-constraint k )) z r is the name of the relation z each A i is an attribute name in the schema of relation r z D i is the data type of values in the domain of attribute A i Example: create table branch ( branch_name char(15) not null, branch_city char(30), assets integer) Silberschatz, Korth and Sudarshan...
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ch3 - Database System Concepts, 5th Ed . Silberschatz,...

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