SQL VISUAL QUICKSTART GUIDE- P2:SQL (pronounced es-kyoo-el) is the standard programming language for creating, updating, and retrieving information that is stored in databases. With SQL, you can turn your ordinary questions (“Where do our customers live?”) into statements that your database system can understand (SELECT DISTINCT city, state FROM customers;) | This page intentionally left blank I Introduction SQL pronounced es-kyoo-el is the standard programming language for creating updating and retrieving information that is stored in databases. With SQL you can turn your ordinary questions Where do our customers live into statements that your database system can understand SELECT DISTINCT city state FROM customers . You might already know how to extract this type of information by using a graphical query or reporting tool but perhaps you ve noticed that this tool becomes limiting or cumbersome as your questions grow in complexity that s where SQL comes in. You also can use SQL to add change and delete data and database objects. All modern relational database management systems DBMSs support SQL although support varies by product more about that later in this introduction . This new edition of SQL Visual QuickStart Guide covers the most recent versions of popular DBMSs adds a chapter on SQL tricks and includes new programming tips new sidebars on subtle or advanced topics and other odds and ends. Introduction xi Introduction About SQL About SQL SQL is A programming language Easy to learn Declarative Interactive or embedded Standardized Used to change data and database objects Not an acronym A programming language. SQL is a formal language in which you write programs to create modify and query databases. Your database system executes your SQL program performs the tasks you ve specified and displays the results or an error message . Programming languages differ from natural spoken languages in that programming languages are designed for a specific purpose have a small vocabulary and are inflexible and utterly unambiguous. So if you don t get the results you expect it s because your program contains an error or bug and not because the computer misinterpreted your instructions. Debugging one s programs is a cardinal programming task. SQL like any formal language is defined by rules of syntax which determine the words and .
