The Structured Query Language (SQL) has become the universal language of choice for DBMS products. A study of this language is therefore imperative for the student of computer science or computer information systems. This and the next few chapters will help you acquire a working knowledge of the language, as implemented in the Oracle environment. One fact you need to be immediately cognizant of is that there are different implementations of SQL. However, the implementations usually have more in common than differences; therefore, once you have mastered the language in one DBMS environment, adjusting to another environment is a trivial matter. This brief chapter provides you with an overview of the language, advancing through the following sections.