Quickest way of fetching a Single row and column in MySQL using DBI

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Quickest way of fetching a Single row and column in MySQL using DBI by cchampion (Curate) on Aug 06, 2006 at 22:00 UTC
You can find plenty of DBI performance info in some of our Tutorials. Most informative for your purposes are Speeding up the DBI and DBI recipes.	[reply]
Re: Quickest way of fetching a Single row and column in MySQL using DBI by Anonymous Monk on Aug 06, 2006 at 21:38 UTC
Nvm...found it. for future ref. `my $id = $dbh->selectrow_arrayref("SELECT id FROM users where username + = '$username'");` [download]	[reply] [d/l]
Re^2: Quickest way of fetching a Single row and column in MySQL using DBI by cees (Curate) on Aug 07, 2006 at 01:04 UTC
Although your version works, it is potentially open to an SQL injection attack through the $username variable. With DBI that is easy to avoid by using placeholders. Also, I think you want selectrow_array (selectrow_arrayref returns a reference to an array, wheras selectrow_array will return a list, or just a scalar value if you are selecting a single column). `my $id = $dbh->selectrow_array("SELECT id FROM users where username = +?", {}, $username);` [download]	[reply] [d/l]
Re^3: Quickest way of fetching a Single row and column in MySQL using DBI by perrin (Chancellor) on Aug 07, 2006 at 16:15 UTC
I think you need array context there: `my ($id) = $dbh->selectrow_array("SELECT id FROM users where username += ?", {}, $username);` [download]	[reply] [d/l]
Re^4: Quickest way of fetching a Single row and column in MySQL using DBI by cees (Curate) on Aug 07, 2006 at 18:01 UTC
Re^5: Quickest way of fetching a Single row and column in MySQL using DBI by jZed (Prior) on Aug 09, 2006 at 01:59 UTC
Re: Quickest way of fetching a Single row and column in MySQL using DBI by runrig (Abbot) on Aug 07, 2006 at 16:39 UTC
Should I even bother using a prepare cache statement for the query? That depends on whether or not you're executing the statement multiple times. In MySQL, you get less benefit in pre-preparing your statements than in some other databases, but the answer is that you can prepare it once if you want to since selectrow_array() (which there are other examples of in this thread) accepts either a SQL statement or a previously prepared statement handle as it's first argument. Also, depending on how often you're executing the lookup in your program, and how large the table is, you may want to just read the whole table into a hash array.	[reply]