Mahler has divided this tutorial on the 4GL language of the Informix relational database management system into two parts. The first part, an introduction to relational database systems and design, contains six chapters: “An Overview of Relational Database Management,” “Relational Database Architecture,” “Relational Database Structure,” “Operations on Relations,” “Indexing and Accessing a Database,” and “Logical Database Design.” The second part, a tutorial on Informix-4GL, contains eight chapters: “Informix-4GL Overview,” “Running Informix-4GL,” “Defining and Using Data,” “Creating and Changing a Database,” “Accessing the Data in a Database,” “Flow of Control, Scope of Control,” “Displaying Data,” and “Reports.”

The first part fails to fulfill its goal of being an introduction to basic relational concepts. The descriptions of some concepts are confusing and leave many unanswered questions. It is not clear, for example, why certain design principles are recommended (for example, why should an attribute name consist of two parts?) or how certain concepts, such as referential integrity, are supported by Informix. Thus, while referential integrity is presented as an essential concept, Mahler does not mention how referential integrity rules can be maintained in Informix. (Informix does not directly support referential integrity mechanisms, but Informix-4GL in conjunction with other Informix utilities may provide a way of enforcing the referential integrity rules.) The book would gain by limiting this part to the relational concepts that are necessary for presenting the tutorial, extending the description of these concepts, and paying more attention to important details (for example, the outer-join mentioned in chapter 4 is actually a left, rather than general, outer-join).

The second part of the book is a well-written tutorial on Informix-4GL. No previous experience with databases or programming languages is necessary to read this part. Informix-4GL is a language that allows the use of SQL operations in a third-generation programming language environment. It is a powerful and useful database language. It is not unique, however, since other relational database management systems (such as Ingres and Sybase) provide similar capabilities. The examples in this part are clear and illustrate the various constructs of Informix-4GL well.

The book contains references only to two Informix manuals and one textbook on relational database systems. Additional references to texts on database design, the SQL language, and relational database management systems would be  helpful.