tailieunhanh - Oracle Database 10g A Beginner's Guide phần 2

Tham khảo tài liệu 'oracle database 10g a beginner's guide phần 2', công nghệ thông tin, cơ sở dữ liệu phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | This document is created with the unregistered version of CHM2PDF Pilot Team Fly r hk Page 33 CHAPTER 2 SQL Structured Query Language CRITICAL SKILLS Learn the SQL Statement Components Use Basic insert and select Statements Use Simple where Clauses Use Basic update and delete Statements Order Data Employ Functions String Numeric Aggregate No Grouping Use Dates and Data Functions Formatting and Chronological Employ Joins ANSI vs. Oracle Inner Outer Self Learn the group by and having Clauses Learn Subqueries Simple and Correlated Comparison with Joins Use Set Operators Union Intersect Minus Use Views Learn Sequences Just Simple Stuff Employ Constraints Linkage to Entity Models Types Deferred Enforced Gathering Exceptions This document is created with the unregistered version of CHM2PDF Pilot Format Your Output with SQL Plus Team Fly Previous Nexl This document is created with the unregistered version of CHM2PDF Pilot Team Fly Page 34 Previous Nexl SQL is the fundamental access tool of the Oracle database in fact it is the fundamental access tool of all relational databases. SQL is used to build database objects and it is also used to query and manipulate both these objects and the data they may contain. You cannot insert a row of data into an Oracle database unless you have first issued some basic SQL statements to create the underlying tables. While Oracle provides SQL Plus a SQL tool that enables you to interact with the database there are also many GUI tools that can be used which then issue SQL statements on your behalf behind the scenes. CRITICAL SKILL Learn the SQL Statement Components Before learning many of the SQL commands that you will use frequently first let s take a look at the two different categories into which SQL statements are classified. They are DDL or data definition language and DML or data manipulation language. The majority of this chapter will deal with the latter. DDL DDL