DBIx::Simple INSTALLATION To install this module do the following: Download the .tar.gz Unpack the .tar.gz, Type: perl Makefile.PL make make test make install Or, with the wonderful CPANPLUS module, just type in its shell: i DBIx::Simple COPYRIGHT AND LICENSE Use this module the way you want to use it, but if anything goes wrong, it's not my fault :) Copyright (C) 2002 J. Waalboer __POD2TEXT__ NAME DBIx::Simple - Easy-to-use OO interface to DBI, capable of emulating subqueries SYNOPSIS General #!/usr/bin/perl -w use strict; use DBIx::Simple; # Instant database with DBD::SQLite my $db = DBIx::Simple->connect('dbi:SQLite:dbname=file.dat'); # MySQL database my $db = DBIx::Simple->connect( 'DBI:mysql:database=test', # DBI source specification 'test', 'test', # Username and password { RaiseError => 1 } # Additional options ); # Abstracted example: $db->query($query, @variables)->what_you_want; Simple Queries $db->query('DELETE FROM foo WHERE id = ?', $id); die $db->{reason} if not $db->{success}; for (1..100) { $db->query( 'INSERT INTO randomvalues VALUES (?, ?)', int rand(10), int rand(10) ); } $db->query( 'INSERT INTO sometable VALUES (??)', $first, $second, $third, $fourth, $fifth, $sixth ); # (??) is expanded to (?, ?, ?, ?, ?, ?) automatically Single row queries my ($two) = $db->query('SELECT 1 + 1')->list; my ($three, $four) = $db->query('SELECT 3, 2 + 2')->list; my ($name, $email) = $db=>query( 'SELECT name, email FROM people WHERE email = ? LIMIT 1', $mail )->list; Fetching all rows in one go One big flattened list (primarily for single column queries) my @names = $db->query('SELECT name FROM people WHERE id > 5')->flat; Rows as array references for my $row ($db->query('SELECT name, email FROM people')->arrays) { print "Name: $row->[0], Email: $row->[1]\n"; } Rows as hash references for my $row ($db->query('SELECT name, email FROM people')->hashes) { print "Name: $row->{name}, Email: $row->{email}\n"; } Fetching one row at a time Rows as lists { my $result = $db->query('SELECT name, email FROM people'); while (my @row = $result->list) { print "Name: $row[0], Email: $row[1]\n"; } } Rows as array references { my $result = $db->query('SELECT name, email FROM people'); while (my $row = $result->array) { print "Name: $row->[0], Email: $row->[1]\n"; } } Rows as hash references { my $result = $db->query('SELECT name, email FROM people'); while (my $row = $result->hash) { print "Name: $row->{name}, Email: $row->{email}\n"; } } Building maps (also fetching all rows in one go) A hash of hashes my $customers = $db -> query('SELECT id, name, location FROM people') -> map_hashes('id'); # $customers = { $id => { name => $name, location => $location } } A hash of arrays my $customers = $db -> query('SELECT id, name, location FROM people') -> map_arrays(0); # $customers = { $id => [ $name, $location ] } A hash of values (two-column queries) my $names = $db -> query('SELECT id, name FROM people') -> map; # $names = { $id => $name } Subquery emulation $db->esq(1); my @projects = $db->query( ' SELECT project_name FROM projects WHERE user_id = ( SELECT id FROM users WHERE email = ? ) ', $email )->flat; DESCRIPTION This module is aimed at ease of use, not at SQL abstraction or efficiency. The only thing this module does is provide a bone easy interface to the already existing DBI module. With DBIx::Simple, the terms dbh and sth are not used in the documentation (except for this description), although they're omnipresent in the module's source. You don't have to think about them. A query returns a result object, that can be used directly to pick the sort of output you want. There's no need to check if the query succeeded in between calls, you can stack them safely, and check for success later. This is because failed queries have dummy results, objects of which all methods return undef. DBIx::Simple object methods "DBIx::Simple->connect( ... )" This argument takes the exact arguments a normal "DBI->connect" would take. It's the constructor method, and it returns a new DBIx::Simple object. See also the DBI manpage. "query($query, @values)" This calls DBI's "prepare" and "execute" methods, passing the values along to replace "?" placeholders. "query" returns a new DBIx::Simple::Result object (or DBIx::Simple::Dummy), that can be used immediately to get data out of it. You should always use placeholders instead of the variables themselves, as DBI will automatically quote and escape the values. DBIx::Simple provides an omniholder placeholder that will expand to "(?, ?, ...)" with as many question marks as @values. There can be only one omniholder, and since it uses all given values, you shouldn't combine it with normal placeholders. This feature was inspired by the EZDBI module. "omniholder($new_value)" This sets the omniholder string. Use "undef" or an empty string to disable this feature. Please note that the given $new_value is not a regex. The default omniholder is "(??)". "emulate_subqueries($bool)", "esq($bool)" - EXPERIMENTAL Sets if DBIx::Simple should enable subquery emulation. Many databases, like Postgres and SQLite have support for subqueries built in. Some, like MySQL, have not. True ("1") enables, false ("0") disables. Defaults to false. In normal MySQL, one would probably use "SELECT projects.project FROM projects, users WHERE project.user_id = users.id AND user.email = ?" to select the projects that belong to the user with a certain email address. Postgres people would write "SELECT project FROM projects WHERE user_id = (SELECT id FROM users WHERE email = ?)" instead. Subqueries can make complex queries readable, but MySQL doesn't have them and many people use MySQL. Now they can have subqueries too! Emulation is done by simply doing multiple queries. This feature is experimental. Please let me know if it works and if you like it. Send your comments to . Even if everything goes well, I'd like to get some feedback. "commit", "rollback" These just call the DBI methods and Do What You Mean. "disconnect" Does What You Mean. Also note that the connection is automatically terminated when the object is destroyed and that all statements are finished when the database object is destroyed. "disconnect" also destroys all active statements. DBIx::Simple::Result object methods "new" The constructor should only be called internally, by DBIx::Simple itself. Some simple minded garbage collection is done in DBIx::Simple, and you shouldn't be directly creating your own result objects. The curious are encouraged to read the module's source code to find out what the arguments to "new" are. "list" "list" Returns a list of elements in a single row. This is like a dereferenced "$result->array". In scalar context, returns only the first value of the row. "array" and "hash" These methods return a single row, in an array reference, or a hash reference, respectively. Internally, "fetchrow_arrayref" or "fetchrow_hashref" is used. "flat" "flat" Returns a list of all returned fields, flattened. This can be very useful if you select a single column. Consider "flat" to be "list"'s plural. "arrays" and "hashes" These methods return a list of rows of array or hash references. Internally, "fetchall_arrayref" is dereferenced, or a lot of "fetchrow_hashref" returns are accumulated. "map_arrays($column_number)" and "map_hashes($column_name)" These methods build a hash, with the chosen column as keys, and the remaining columns in array or hash references as values. For "map_arrays", the column number is optional and defaults to 0 (the first column). The methods return a reference to the built hash. "map" Returns a reference to a hash that was built using the first two columns as key/value pairs. Use this only if your query returns two values per row (other values will be discarded). "rows" Returns the number of rows. This function calls DBI's rows method, and may not do what you want. See the DBI manpage for a good explanation. "finish" Although it is much easier to just have the result object go out of scope, you can explicitly end the statement with this method. There should be no reason to use this method. Just let it go out of scope. FEEDBACK I'd like to hear from you what you think about DBIx::Simple, and if it has made your life easier :). If you find serious bugs, let me know. If you think an important feature is missing, let me know (but I'm not going to implement functions that aren't used a lot, or that are only for effeciency, because this module has only one goal: simplicity). My email address can be found near the end of this document. BUGS Nothing is perfect, but let's try to create perfect things. Of course, this module shares all DBI bugs. If you want to report a bug, please try to find out if it's DBIx::Simple's fault or DBI's fault first, and don't report DBI bugs to me. Note: the map functions do not check if the key values are unique. If they are not, keys are overwritten. DISCLAIMER No warranty, no guarantees. I hereby disclaim all responsibility for what might go wrong. AUTHOR Juerd SEE ALSO the DBI manpage