Conclusion

Today, most database software (DBMS) is based on the relational model. A database is seen as a set of tables, structured according to normal forms and manipulated using non-algorithmic languages, the best-known representative of which is SQL.

This article successively presents :

• the table normalization process to avoid data inconsistencies during updates;

• operations on tables to extract the required data ;

• SQL language for expressing retrieval queries ;

• implementation of SQL queries in an application program written in Java.

The relational model is well suited to describing data in business applications. However, multimedia applications handling complex objects require more elaborate...