Health Data Clinic - Book 7: SQL JOINs

Answers usually live in more than one table. A JOIN is how you bring them back together, and this book covers all four types properly. You start with the shared bridge column that makes any join possible, write your first INNER JOIN, and pick up table aliases and column aliases with AS so long queries stay readable. Sorting and filtering a joined result each get their own chapter, since a WHERE on a joined set behaves differently from what beginners expect. Then the four types are worked one by one, INNER, LEFT, RIGHT and FULL OUTER, with the exact rows each keeps and drops printed for you. From there you move to three tables at once in two shapes, the chain and the bridge, and to lookup tables that turn stored codes into words a human can read. A closing chapter answers the question people actually have, which is which join to reach for.

Twenty-seven A4 pages, in full color. Written in short sentences and plain English, for readers whose first language is not English and clearer for everyone else because of it.

Every query in this book was run against a live database before the page was printed, so the result you read is the result you get. Instant PDF download. By M.R. Sterling.