INFORMIX-SQL is a relational database management system running under the UNIX operating system+. It is becoming the relational database management system of choice in MS-DOS, OS/2 and networking environments. INFORMIX-SQL: A Tutorial and Reference has been designed as a comprehensive, self-instruction book to enable the reader to quickly get the most out of INFORMIX-SQL. Features include: version 2.10.03 with complete references to facilities that are available with version 4.0, including the use of BLOBs; practical examples and exercises throughout to enable the reader to create a complete database/application; and shortcuts and information not contained in the documentation manuals, for example how do you add a serial column to a table already containing data? does an index always speed up a query? and how can you use variables in SQL statements, without leaving the SQL editor? Information about a particular feature is dealt with under one heading and graded into text and reference notes. The text is mainly intended for the beginner and the notes for the experienced user. The differences between INFORMIX-SQL and INFORMIX-4GL are discussed, explaining when one, or both products are needed.