Re: fetchOne vs. fetchAll vs. Sql's limit

On 23 Oct 2011, at 06:52, AmirBehzad Eslami wrote: > Dear list, > As you already know, there are different ways to retrieve a record-set > from a database. For example, here's the classic way to perform this in PHP: > > while ($row = mysql_fetch_assoc($db)) { > // my row is available here > } > > Speacking about PHP internals, what exactly happens here? > 1) The PHP asks the Database-Layer to give a record in each while pass? > I mean the record-set is not available in PHP's memory, but in MySQL's Mem. > > 2) Or the database-layer has gave the whole result-set to PHP, and we're > just fetching a single row from PHP's memory? It depends what function was used to do the query... mysql_query will fetch all result rows from MySQL into a buffer. mysql_unbuffered_query does not. Read the documentation for mysql_unbuffered_query carefully before you start using it: http://php.net/mysql_unbuffered_query > 3) Finally, what is the efficient way to retrieve thousands or records which > need to be processed at once? Using LIMIT? Yes, use mysql_buffered_query, or mysql_query with limit to work through the results in a paginated fashion. -Stuart -- Stuart Dallas 3ft9 Ltd http://3ft9.com/