Health Data Clinic - Book 10: Querying & Filtering Data

Getting the rows you want, and no others. This book takes the SELECT statement apart and then spends most of its pages on the clause that does the real work, WHERE. You start with choosing columns and handling text, numbers and quotes correctly, then move through comparison operators and combining conditions with AND, OR and NOT. BETWEEN handles ranges, IN handles lists, and LIKE with wildcards handles partial text, each with the exact result printed beside the query. From there you shape the output: ORDER BY to sort, DISTINCT to remove duplicate values, and LIMIT to take just the top rows. A chapter on filtering by date deals with the format problems that catch people out. The book ends by explaining the order in which SQL actually reads a query, which is not the order you type it, and which explains most of the errors beginners run into.

Twenty-five 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.