Welcome to this edition of A Primer on SQL. As you would be able to see, the book is fairly short and is intended as an introduction to the basics of SQL. No prior experience with SQL is necessary, but some knowledge of working with computers in general is required. My purpose of writing this was to provide a gentle tutorial on the syntax of SQL, so that the reader is able to recognize the parts of queries they encounter and even be able to write simple SQL statements and queries themselves. The book however is not intended as a reference work or for a full time database administrator since it does not have an exaustive topic coverage.
This edition features a new chapter on subqueries and a few other changes suggested by readers. There is also some further information about using this text with SQLite which has continued to soar new heights in popularity, while Ingres has seen some slowness in recent times. However, this text remains database implementation agnostic.