Chapter 7 SQL

In this chapter, we elaborate on SQL which is the lingua franca of RDBMSs and one of the most popular data definition and manipulation languages in use in the industry nowadays. Its core functionality is implemented, with only some minor variations, throughout all RDBMS products. We discuss the SQL language constructs to express a relational model and to formulate queries that retrieve and modify the data in a relational database.
First, we provide an overview of the SQL Data Definition Language (SQL DDL) to define a relational data model. We also discuss how the SQL Data Manipulation Language (SQL DML) can be used for data manipulation such as retrieving data, updating data, inserting new data and deleting existing data. We then elaborate on SQL views and SQL indexes, which are part of the external and internal data model, respectively. We also illustrate how SQL can be used for authorization by granting or revoking privileges to users or user accounts. The chapter concludes by illustrating how SQL can be used for managing metadata.