SQL is the point at which careful relational design pays off. As you have seen with both the DML and DDL statements, the primary rule of relational databases, non-redundancy, creates an environment in which there can be only one correct set of responses to any query The depth of the SQL constructs supported by Local SQL makes this language within a language, the Delphi development environment, an important skill to obtain. We will discuss these statements again when the components that use them are explored.

This is the last chapter on the theoretical aspects of database development. You have reviewed the theory behind the relational database paradigm and, hopefully, have gained some new insight into the importance of following this model in your development efforts. You have the tools and the knowledge to effectively design a relational system; now we will explore the tools that Delphi provides to do so.

Chapter 3-Structured Query Language ■ 71

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