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Chapter 3: SQL and QBE Transparencies

Purpose and importance of SQL, the main language for querying relational databases. How to retrieve data using the SELECT statement. How to insert data using the INSERT statement. How to update data using the UPDATE statement. How to delete data using the DELETE statement. About an alternative language for querying relational databases called QBE. | SQL and QBE Transparencies Chapter Name September 98 Chapter 3 - Objectives Purpose and importance of SQL, the main language for querying relational databases. How to retrieve data using the SELECT statement. How to insert data using the INSERT statement. How to update data using the UPDATE statement. How to delete data using the DELETE statement. About an alternative language for querying relational databases called QBE. Chapter Name September 98 Structured Query Language (SQL) Main language for relational DBMSs. Main characteristics: Relatively easy to learn Non-procedural - you specify what information you require, rather than how to get it Essentially free-format Consists of standard English words like SELECT, INSERT, and UPDATE Can be used by range of users. Chapter Name September 98 Structured Query Language (SQL) First and, so far, only standard database language to gain widespread acceptance. Huge investment from both vendors and users. Federal Information | SQL and QBE Transparencies Chapter Name September 98 Chapter 3 - Objectives Purpose and importance of SQL, the main language for querying relational databases. How to retrieve data using the SELECT statement. How to insert data using the INSERT statement. How to update data using the UPDATE statement. How to delete data using the DELETE statement. About an alternative language for querying relational databases called QBE. Chapter Name September 98 Structured Query Language (SQL) Main language for relational DBMSs. Main characteristics: Relatively easy to learn Non-procedural - you specify what information you require, rather than how to get it Essentially free-format Consists of standard English words like SELECT, INSERT, and UPDATE Can be used by range of users. Chapter Name September 98 Structured Query Language (SQL) First and, so far, only standard database language to gain widespread acceptance. Huge investment from both vendors and users. Federal Information Processing Standard (FIPS). Used as the basis for other standards. ANSI and ISO standard is now the defining language for relational databases. Chapter Name September 98 Objectives of SQL Ideally database language should let user: create database and table structures; perform basic tasks like insert, update, delete; perform both simple and complex queries. Must perform these tasks with minimal user effort. Must be portable. Chapter Name September 98 Writing SQL Commands SQL statement consists of reserved words and user-defined words. Reserved words are a fixed part of SQL and must be spelt exactly as required and cannot be split across lines. User-defined words: made up by user and represent names of various database objects such as tables, columns, views. Chapter Name September 98 Literals Literals are constants used in SQL statements. All non-numeric literals must be enclosed in single quotes (eg. ‘New York’). All numeric literals must not be enclosed in .