Database Modeling & Design Fourth Edition- P46: Database technology has evolved rapidly in the three decades since the rise and eventual dominance of relational database systems. While many specialized database systems (object-oriented, spatial, multimedia, etc.) have found substantial user communities in the science and engineering fields, relational systems remain the dominant database technology for business enterprises. | Appendix The Basics of SQL Structured Query Language or SQL is the ISO-ANSI standard data definition and manipulation language for relational database management systems. Individual relational database systems use slightly different dialects of SQL syntax and naming rules and these differences can be seen in the SQL user guides for those systems. In this text as we explore each step of the logical and physical design portion of the database life cycle many examples of database table creation and manipulation make use of SQL syntax. Basic SQL use can be learned quickly and easily by reading this appendix. The more advanced features such as statistical analysis and presentation of data require additional study and are beyond the reach of the typical nonprogrammer. However the DBA can create SQL views to help nonprogrammers set up repetitive queries other languages such as forms are being commercially sold for nonprogrammers. For the advanced database programmer embedded SQL in C programs for instance is widely available for the most complex database applications which need the power of procedural languages. This appendix introduces the reader to the basic constructs for the SQL-99 and SQL-92 database definition queries and updates through a sequence of examples with some explanatory text. We start with a definition of SQL terminology for data types and operators. This is followed by an explanation of the data definition language DDL constructs using the create table commands including a definition of the various 213 214 Appendix The Basics of SQL types of integrity constraints such as foreign keys and referential integrity. Finally we take a detailed look at the SQL-99 data manipulation language DML features through a series of simple and then more complex practical examples of database queries and updates. The specific features of SQL as implemented by the major vendors IBM Oracle and Microsoft can be found in the references at the end of this appendix. SQL .
