Re: & and && and weird results

PJ, On Wed, Apr 1, 2009 at 1:40 PM, PJ <af.gourmet@videotron.ca> wrote: > SELECT * FROM book > WHERE id IN (SELECT bookID > FROM book_author WHERE authID IN (SELECT author.id > FROM author WHERE LEFT(last_name, 1 ) = '$Auth' && > LEFT(last_name, 1 ) = '$Auth1' && LEFT(last_name, 1 ) = '$Auth2')); > Say $Auth = "I", $Auth1 = "J", $Auth2 = "K". The above sub-query is stating select author ids where the first digit in last_name is I AND the first digit in last_name is J AND the first digit in last_name is K. For any given last_name (thus, author id), the first digit can only be one of those options, thus this sub-query will return ZERO results. To get a sub-query that will only return results that start with I, J, or K,you can instead use the following sub-query: SELECT author.id FROM author WHERE LEFT(last_name, 1) = '$Auth' OR LEFT(last_name, 1) = '$Auth1' OR LEFT(last_name, 1) = '$Auth2' The above will return all author IDs where the surname starts with I, J, or K. - Lex